Communication difficulties with advisors - starting to impede work I could use some advice about my relationship with my doctoral advisors. Some context:

I'm about 1 year and 8 months into my PhD.
My program has relatively heavy course requirements. I have now finished most of my coursework, but much of my efforts until recently were focused on courses.
My field is relatively new, and very interdisciplinary. There are a lot of foundational challenges especially regarding synthesizing methodology from different contributing fields that haven't really been solved yet. My advisor is an expert in one of the fields, but not in the others.
Seven years ago, I was diagnosed with what is essentially schizophrenia and depression. It is still a struggle to manage symptoms, and that is not likely to change. My collegaues know about the issues in generalities, but I have not shared specifics due to bad previous experiences.

With respect to research, I have about 100 typed-out pages summarizing key related/foundational work, outlining my project methodology, system design and research questions. It's a lot of work, and I think it's very useful, but it's not results, and hence no publications. My advisors aren't happy with this.
Besides having no publications, they seem to think that I have focused too much on groundwork, and that my thesis's scope is too large. I know they are right about the scope -- in fact, we recently renegotiated the scope after my initial literature review revealed many unanswered questions that we would've had to address.
Since then, they really want me to (1) get some initial results, and (2) focus on one thing at a time. I am trying to do this, and expect to have initial results within a week. Still, in general, this is a problem for me:

I'm not used to working on one thing at a time. In my experience, working on a project usually involves working on 2-3 sub projects with the intention of integrating them at the next step, so that issues on one sub-task won't invalidate work on other sub-tasks.
I feel like we need a broader vision for where this is heading before we start potentially wasting time heading down one path.
Focusing on one thing is hard for me due to my mental heath issues. I don't always have control over what subject matter I'm able to process. I've found the best way to be productive is to switch between multiple tasks. The problem is related to focus, not to my understanding of the subject matter.

I haven't been able to discuss any of this with my advisors (and the last one in particular would require a discussion of my mental health, which I don't want to do). But leaving it unaddressed is also not working -- whenever I mention anything other than working on this one narrow task that we have all agreed that I should work on, it's shut down immediately under the heading of &quot;you need to focus on this one thing.&quot; In fact, this recently led to a condescending and rude email from my advisor, which was really upsetting.
Another issue is an upcoming symposium. The head of my research group recently mentioned an online symposium on a topic that I think will be useful. Further, there is a good opportunity for me to present my &quot;new research directions.&quot; I could easily put something together and attend the webinar, but I would have to talk to my advisor first. I have an (I think reasonable) anxiety that if I try to broach this subject, it will immediately be shot down and it will make him even more frustrated.
How should I approach this? Any advice is appreciated.
I think the core issue you are describing is relevant for many PhD students. Your mental health may excabate the effects, but does not seem central to the situation to me.
A PhD is a journey through uncharted territory, and that can feel uncomfortable. So in particular for industrious students, there always is a temptation to to not go where the dragons are yet, but to prepare just a little bit better - maybe read another paper for the literature review, revise the project proposal again, those things. But even within a single field, it will almost always be impossible to read all potentially relevant literature. At some point, a PhD student just has to take the leap.
For me in math/TCS, its just my own time which is on the line when doing research. Sure, maybe if I had read another paper I'd have seen that the theorem is already known, or found an incredibly useful ingredient to make the proof easier - but the time I spent trying to proof it still isn't wasted, as I learn from how I tried it. I'll concede that if you are eg doing experiments with animals or expensive chemicals, you do need to prepare well - but the point remains, at some point you need to do.
Polishing aside, you have 100 pages worth of research proposal + literature review. That is an enormous amount for what I am used to - 30 pages already seems pretty extensive to me. For a supervisor, getting a student to take this leap is something you can influence only in a limited way. So I can empathize with your supervisors frustration (although this doesnt excuse the mean remarks).
When it comes to the issue of preferring to have multiple active tasks, and to work on the best match to one's current mental state: I share that preference, and I think it is explainable very well without referring to any medical diagnosis. The moment to bring that up probably is once you have completed your designated task; and you should make clear that you understand that these tasks need to move you forward.