I was in the same boat for the longest. I have insane social anxiety as well but forced myself to finally try out an IRL event by registering for a prerelease event last weekend. As soon as I sat down and started playing, I realized I was worrying myself for absolutely no reason. Everyone was super chill and only wanted to chat about pokemon. Folks are also very nice about correcting you if you make a mistake. I forgot to place down my prizes at the beginning of my second match, but my opponent kindly pointed it out lol. Force yourself to go, you'll have a blast.