As someone who is slowly recovering from anxiety issues that came from similar-ish circumstances, I definitely think it's the main issue.

First, there is a very direct link between anxiety and short-term memory loss. You also indicate that you have lost friends of this... definitely makes me think it's anxiety-related, as people hate to be around people who are quiet or worrying (because we're all kind of assholes).

The 2 things that help me with anxiety are to remember that people will find a reason to judge you for literally anything no matter what you do. People do it all the time. I'll be driving down the street and if I'm not in the right mood, if someone even slightly hits their brakes in front of me I start finding any reason at all to hate them. And people may have just been uncomfortable. I know I've stopped hanging out with people who I thought could get me into trouble. Being the hardest partier is not a good thing.

But the other thing to remember is that these judgements don't last forever. A lot of times, they're gone in a second. Most people won't have a real deep dislike for you unless you did something to deliberately hurt them. That doesn't mean they'll actively like you. But something that high school kids need some perspective on is that for most people, the base state is not people liking each other in any arena in life. There are few people I come across on a daily basis that I would ever want to hang out with, but I'm fine with them, I might even have a kind of affection for them, I just don't want to get bogged into a conversation with them.

If there's someone that you haven't specifically wronged or crossed and they actively dislike you, that means they have the problem. For instance, a really religious or sheltered kid might not like you for doing that much acid because they wish they had the kind of freedom you do.

As for your anxiety about your brain, all you can do is accept the way things are. Not as broken, but just as the way it is. Try to think in the growth mindset. The only thing in your control is the direction you move, not where you stand today. Dwelling on what could have been is pointless because it's just not a reality of this universe.

Drugs are fun, but they do tend to pull you away from the reality of this universe, and the more time you spend in other universes, the less you have to achieve goals in this one. The less tethered you are to this reality, the more you space out in conversations and don't concentrate on what's happening around you. And if you want to get along with people, you have to focus on what they're doing as well as what you're doing, and try to help them with it and come up with fun things to do together.

There's a book i read called "suspicious minds: how culture shapes madness." It was directly related to things I was experiencing, which you haven't indicated you have experienced. But since I read it, I've had much, much less anxiety about my own mental state. But, I think it's a good book to just understanding human psychology, which might help you understand a little more what you're experiencing.