user-1: I'm currently attempting to do shamatha and vipassana meditations in alternation, even though I'm unsure this is the best way to proceed. I noticed that generally, as a person, I am somewhat repressed in the sense that few thoughts, images or sensations seem to emerge. 
There are a few other peculiarities I experience, and I'm unsure if people could help me with that. I remember vaguely as a child having odd sensations / visions which arose without reason, in mandala form usually. And since a while now, I seem to be gaining insight randomly, sporadically. I've been happy for years, not in a strong pleasant sensation but in experiencing equanimity generally or lack of attachments. 
Yet, I'm feeling stuck in my practice because I don't seem to realize where I'm at. I don't know whether I have good or bad concentration, or whatever else. I seem to be unaware of my own mental states. Since I feel repressed and few images or feelings arise, I think perhaps vipassana would help, but ultimately, I dunno.
Any kind of help on what I'm experiencing would aid me greatly, and I'd be willing to supply more details if necessary.

user4753: My guess (from the brief description, which somewhat resonates with my previous experiences) is that your mind is in a partially frozen or disconnected/dissociated state. Equanimity is a netural feeling (from the set +/0/-), not absence of feelings. It can be a happy state in some sense, but it is not alive. Sometimes people don't realize that they are in such a state until they get out and feel the difference. One way of describing depression is that it is a state of disconnection (rather than a state of unhappy feeling); I am not diagnosing you, but it might be something in that direction (you say "repressed").
My recommendation is to do vipassana. Do vipassana which only involves very little concentration ("dry vipassana"), otherwise your mind will be using concentration (fake calmness and equanimity) to hide stuff; you want to see it and release it as much as possible. I have a very good experience with Ajahn Tong's tradition, which is Mahasi with some Thai influences; they have a set "basic course" of 2-3 weeks and use noting to help develop mindfulness. Noting is useful, because it forces you to note something all the time (even if "disconnected", "frozen", "equanimous", "nothing", "unconcentrated", "confused"), thus making it more difficult for the mind to hide somewhere and develop attachment to some states. Do the full course if you can, it is very powerful.
To connect with the theory a bit, you are seeing one of the roots of suffering, namely ignorance -- not knowing what is happening. It is tough to see (tougher than greed and hatred, the other 2) because one literally does not know that one does not know. Something like curved space making light go around something, but it can only be identified indirectly and it looks like "nothing".
If you locate yourself, I can help you find centers in your area (they have in Thailand, Europe, Central America; and occasionally courses here and there).

user8157: Your question gives the impression that you have not developed meditation within a certain teaching/practise tradition for a prolonged period but have been learning theory from different random sources. If that is true, your question thus gives the impression the various theories of meditation have confused you. 
In the West, there is a popular form of 'meditation' from Burma that is erroneously called 'vipassana', where practitioners are preoccupied with noting thoughts, images or sensations. This is so because practitioners have many distractions so this method accommodates & attracts those kinds of practitioners.  
In formal Buddhist theory (such as in the old scriptures) having few thoughts, images or sensations is a good thing. In formal Buddhist theory, samatha & vipassana are developed in tandem (concurrently), with samatha predominating in the beginning & vipassana developing naturally as samatha deepens. 
In formal Buddhist theory, 'vipassana' does not mean noting thoughts, images or sensations. 'Vipassana' means 'seeing clearing' the impermanence & selflessness of phenomena. 
For example, on a very basic level, the mind can develop samatha by continuously observing the breathing in a balanced equanimous way. As the mind is continuously observing breathing, it will naturally notice the breathing is impermanent; in that the breathing comes & goes; that it becomes short & long; that the various breaths have different textures & qualities, such as being smooth, rough, agitating, soothing, etc; ultimately to the point of seeing clearly it is the body that breathes (rather than "I" or the "self" that breathes). Seeing clearly the impermanence & selflessness of the various breathing ins & breathing outs is real vipassana. 
Then as samatha develops & deepens, certain feelings of rapture & joy will predominate in the mind. When these feelings predominate, they will also be objects of vipassana, in that the rapture & joy will be seen as dependently arising, impermanent & selfless. 
Then as samatha deepens, more profound vipassana will occur in different ways. 
Therefore, in my opinion, you should consider developing samatha more because this leads to calmness & non-confusion. You should forget about thoughts & images because these are actually hindrances to meditation.
The 'sensations' that are ideally observed are the subtle sensations within the breathing; the sensations of the breathing being smooth, rough, etc. Then later, as samatha is profoundly developed, the mind observes the sensations of rapture & joy that arise from the calming of the breathing. 
After this, the mind will be very clear & can discern the 'dependent origination' of thoughts, consciousness, other mentality & sense objects. 
The classic original Buddhist path is based on developing samatha. Further, based in what you described in your question, the impression is your mind is predisposed or inclined to develop samatha, since it has equanimity & few attachments. 

[And] for him these two qualities occur in tandem: tranquillity (samatha) & insight (vipassana).
Maha-salayatanika Sutta


-1: <p>I'm currently attempting to do shamatha and vipassana meditations in alternation, even though I'm unsure this is the best way to proceed. I noticed that generally, as a person, I am somewhat repressed in the sense that few thoughts, images or sensations seem to emerge. </p>

<p>There are a few other peculiarities I experience, and I'm unsure if people could help me with that. I remember vaguely as a child having odd sensations / visions which arose without reason, in mandala form usually. And since a while now, I seem to be gaining insight randomly, sporadically. I've been happy for years, not in a strong pleasant sensation but in experiencing equanimity generally or lack of attachments. </p>

<p>Yet, I'm feeling stuck in my practice because I don't seem to realize where I'm at. I don't know whether I have good or bad concentration, or whatever else. I seem to be unaware of my own mental states. Since I feel repressed and few images or feelings arise, I think perhaps vipassana would help, but ultimately, I dunno.</p>

<p>Any kind of help on what I'm experiencing would aid me greatly, and I'd be willing to supply more details if necessary.</p>
 4753: <p>My guess (from the brief description, which somewhat resonates with my previous experiences) is that your mind is in a partially frozen or disconnected/dissociated state. Equanimity is a netural feeling (from the set +/0/-), not absence of feelings. It can be a happy state in some sense, but it is not alive. Sometimes people don't realize that they are in such a state until they get out and feel the difference. One way of describing depression is that it is a state of disconnection (rather than a state of unhappy feeling); I am not diagnosing you, but it might be something in that direction (you say "repressed").</p>

<p>My recommendation is to do vipassana. Do vipassana which only involves very little concentration ("dry vipassana"), otherwise your mind will be using concentration (fake calmness and equanimity) to hide stuff; you want to see it and release it as much as possible. I have a very good experience with Ajahn Tong's tradition, which is Mahasi with some Thai influences; they have a set "basic course" of 2-3 weeks and use noting to help develop mindfulness. Noting is useful, because it forces you to note something all the time (even if "disconnected", "frozen", "equanimous", "nothing", "unconcentrated", "confused"), thus making it more difficult for the mind to hide somewhere and develop attachment to some states. Do the full course if you can, it is very powerful.</p>

<p>To connect with the theory a bit, you are seeing one of the roots of suffering, namely ignorance -- not knowing what is happening. It is tough to see (tougher than greed and hatred, the other 2) because one literally does not know that one does not know. Something like curved space making light go around something, but it can only be identified indirectly and it looks like "nothing".</p>

<p>If you locate yourself, I can help you find centers in your area (they have in Thailand, Europe, Central America; and occasionally courses here and there).</p>
 8157: <p>Your question gives the impression that you have not developed meditation within a certain teaching/practise tradition for a prolonged period but have been learning theory from different random sources. If that is true, your question thus gives the impression the various theories of meditation have confused you. </p>

<p>In the West, there is a popular form of 'meditation' from Burma that is erroneously called 'vipassana', where practitioners are preoccupied with noting thoughts, images or sensations. This is so because practitioners have many distractions so this method accommodates &amp; attracts those kinds of practitioners.  </p>

<p>In formal Buddhist theory (such as in the old scriptures) having few thoughts, images or sensations is a good thing. In formal Buddhist theory, <em>samatha</em> &amp; <em>vipassana</em> are developed in tandem (concurrently), with <em>samatha</em> predominating in the beginning &amp; <em>vipassana</em> developing naturally as <em>samatha</em> deepens. </p>

<p>In formal Buddhist theory, 'vipassana' does not mean noting thoughts, images or sensations. 'Vipassana' means 'seeing clearing' the <strong>impermanence</strong> &amp; <strong>selflessness</strong> of phenomena. </p>

<p>For example, on a very basic level, the mind can develop samatha by continuously observing the breathing in a balanced equanimous way. As the mind is continuously observing breathing, it will naturally notice the breathing is impermanent; in that the breathing comes &amp; goes; that it becomes short &amp; long; that the various breaths have different textures &amp; qualities, such as being smooth, rough, agitating, soothing, etc; ultimately to the point of seeing clearly it is the body that breathes (rather than "I" or the "self" that breathes). Seeing clearly the impermanence &amp; selflessness of the various breathing ins &amp; breathing outs is real vipassana. </p>

<p>Then as samatha develops &amp; deepens, certain feelings of rapture &amp; joy will predominate in the mind. When these feelings predominate, they will also be objects of vipassana, in that the rapture &amp; joy will be seen as dependently arising, impermanent &amp; selfless. </p>

<p>Then as samatha deepens, more profound vipassana will occur in different ways. </p>

<p>Therefore, in my opinion, you should consider developing samatha more because this leads to calmness &amp; non-confusion. You should forget about thoughts &amp; images because these are actually hindrances to meditation.</p>

<p>The 'sensations' that are ideally observed are the subtle sensations within the breathing; the sensations of the breathing being smooth, rough, etc. Then later, as samatha is profoundly developed, the mind observes the sensations of rapture &amp; joy that arise from the calming of the breathing. </p>

<p>After this, the mind will be very clear &amp; can discern the 'dependent origination' of thoughts, consciousness, other mentality &amp; sense objects. </p>

<p>The classic original Buddhist path is based on developing samatha. Further, based in what you described in your question, the impression is your mind is predisposed or inclined to develop samatha, since it has equanimity &amp; few attachments. </p>

<blockquote>
  <p><em>[And] for him these two qualities occur in tandem: tranquillity (samatha) &amp; insight (vipassana).</em></p>
  
  <p><em>Maha-salayatanika Sutta</em></p>
</blockquote>
