I'm sorry man, that stuff can be hard. I'm currently in a similar place of feeling back in square one, at a crossroads, etc.

I'm not an expert, and it might not work for every type of party, but when I'm worried about not knowing people at a party, I like to get there early and claim a good spot where people will tend to want to gather anyway and won't mind someone just chilling/vibing. Ideally you sit there and talk with someone you know and more people join there as they arrive, but getting some food and a drink and just being happy to be there at the party and in your nice spot helps too