Hi, I don't know how long ago you posted this thread, if it's old I apologize. I came here because I am having similar issues with clothes shopping. Funny enough my anxiety isn't so bad now that it's been blunted by the anti-depressants I'm on. It hasn't been a big issue in a while. I can actually go into a store by myself, go through the whole process of browsing and shopping. The discomfort and sweaty palms are still there, just not so much that I can't think straight.
My issue now is not so much the act of going out and clothes shopping, I do it once or twice a month, and often find that I am most comfortable doing it at certain times of the day at certain days of the week, like in the middle of the day before the kids are out of school and during the week or on a Sunday, the less busy days. I feel most comfortable going to places outside of where I live. I'm less anxious either in urban places where people don't really recognize me, or in very quiet always empty stores like this peaceful antique shop we have downtown. The lady that works there is really nice in a genuine way.
The problem I have now is that I just literally can't seem to ever be able to piece together a functional outfit. This problem became noticeable to me after I entered my late teens and wanted to be taken more seriously/look pretty. The graphic tee shirts will always have a place in my heart, but I feel ready to move up to the next level. Only problem is I have no bleeping clue what that looks like on me since there are like you said, ZILLIONS of style options.
I get stressed out by a) The choices b) The prices c) Whether it was ethically made d) the fit. I wish I could say that I'm no longer ruled by my social anxiety but I still am. I don't go out sometimes (sometimes frequently) just because I'm afraid people will point out how weird, stupid, or ugly I look. I have encountered these criticisms in the past so I feel like my rational thinking has been warped by these situations. When I leave the house I either am wearing something so neutral that I am confident that no one will see me, or something very noticeably frumpy or funny looking. It's all very exhausting and I wish there was a machine that we could step into and you could just make perfect fitting nice clothes materialize out of thin air. I'm sorry this comment is a novella. Maybe there's something in here that can help you, if not, again I'm sorry. Hope you're doing okay.