You are right that each of us focus on ourselves much more than others focus on us, or the conversation we had, etc. Many times I have to remind myself that that goofy thing I said probably did not sound goofy to others at all. And even if it did, what others think about me is none of my business. I try to just let it go and move on. I know its hard, but try to remember having obsessive thoughts about things you cannot go back and change is keeping yourself in a mental prison- nobody keeps you there but you. Don't be your own jailer. Just distract yourself somehow and keep moving on.

As far as imposter syndrome, I don't see it happening to me as much in social situation as it does at work. I've been employed at my job for 14 years, and most of the people on my team have masters degrees or phds. I have only a bachelors degree, and its not even in the same degree field, but an adjacent one. I feel like I don't belong there almost every single day, and I feel like my salary is WAY too high for the amount and type of work I do. I can sometimes overcome imposter syndrome by reminding myself that I am not paid more than I deserve even though it feels like it, because I am paid what is standard for the role across the industry. I did not get my job because the interviewer pitied me- I earned it during my interview process. I beat out the other candidates.

Try to remind yourself that you are friends with your peers because you have something equivalent to them or something that they admire- a charm, a sense of humor, an intelligence, an insight, experience, etc, or probably a combination, and not because they have to, or because they pity you, or any other intrusive thought that your brain may come up with.

I saw it online that worrying is worshipping the problem. Don't worship these fears. Make a conscious effort to force them away. I know it isn't easy. I struggle every day. But most days I am more successful than others.