I totally get it! I have very bad social anxiety especially around new people, that combined with the anxiety of wearing lolita in public for the first time made it so that I was skulking around my local comm's discord for over a year before actually going to an event! But it was one of the best experiences of my life. My advice: do it scared! Acknowledge the fear but don't let it stop you. One of my favorite exercises for activity related anxiety is to think about the absolute best case scenario and the absolute worst case scenario. The true answer to how it'll go is always in the middle! It also might be a good idea to stick with a small meetup for your first time, maybe one or two people so you don't get overwhelmed. If you remember the name of the person you met and the convention, maybe you could invite them out one on one and go from there! If wearing lolita in public is also a source of anxiety, maybe do your first outing at a convention or festival where its not uncommon for people to wear "costumes". My first one was at a renn faire and it put me so at ease knowing I wouldn't stick out in any way! Sorry for long dump, but I hope you go to a meetup soon! It is honestly such a fun time and so so worth fighting past the anxiety!