Unintentional Plagiarism in my Masters Thesis About four months ago I graduated from a reputable university and received great feedback from the committee who judged my masters defense as well as my thesis. Prior to my defense, I was asked to prepare my paper — not my thesis — within 5 weeks of graduating. There were a few problems regarding the quality and quantity of the data and figuring out the appropriate analysis took considerable time. During this period I wrote and rewrote all the sections that are essential to a paper, keeping in mind that these exact sections would form my thesis as well. A colleague also edited my introduction, at times embellishing my sentences that went beyond what the cited authors stated. The time crunch resulted in lower quality work. 

Once the paper was “approved” I was given the green light to work on my thesis, at just two weeks prior to graduating. All I had to do was copy and paste my paper into my thesis document, but I wanted to improve my literature review and make sure all the sections flowed well. In the end, even my thesis document did not turn out to be at the quality I hoped for. It was well received, but I believe that it is highly unlikely my supervisor even looked at my thesis, much less even read the first few pages.

I just re-read my thesis and upon scrutinizing it I have found that I have unintentionally plagiarized from other authors in different areas, including the literature review, methods and materials, and one line in the introduction, all which was likely due to negligence and carelessness (can I call it that given the time I had?) of finishing on time. I didn’t outright copy, but sentence structure and wording are strikingly similar.

My friends (many who are in academia), family, and therapist (psychologist) have all advised that I use this as a learning experience for the future, as the university nor my supervisor would be willing to give me a second chance as such rarely is offered for something of this magnitude.

At this point I’m looking for any sound advice... What do I do? How do I move past this? I worry about my future :(
While I don't know the policies of your university, nor anything about your advisor, I would suggest that you explore any possible option of submitting a corrected version of the thesis. Explain to your advisor what happened. Be very clear and honest about it. Perhaps they can make an accommodation. The paper, on which it is based can, perhaps, be used to show proper intent. 

If you can't substitute a newer version, you will need to create and try to submit an addendum giving proper credit wherever needed. 

I doubt that the paper is in any danger of being rejected, since the citations are correct there. 

While many might consider this a serious breach, rather than panic and carelessness, I doubt that it would be career ending. Intent matters a lot in such things.