honestly when I go to a convention I'm so much more focused on seeing everything and shopping and actually getting around all the people than I am on what people think of me!
Last Otakon I had my first Artist Alley table though, and that was so nerve-wracking!
Having people appraise my artwork and decide if it was worth buying and taking home scared me half to death, but I sat through it and I had friends help me and people actually seemed to really like my stuff (who wouldn't, for $5 a print lol)
Everyone has their nerves, sounds like it's a serious thing and I totally believe you that it's hard to just get up and deal. I'm sure your friends don't mind helping you out, but I also sympathize with the guilty feeling of doing that. I felt like I took away all of my friends' con time with them helping me out at my table.
But it turned out they were so happy to have a place to sit and a solid meeting spot, they said it was the best and most relaxed con they've ever been to!
So my advice?
Take it slow, take it easy. Arrange a photoshoot with your friends or go to a Cherry Blossom Festival (if there's one near you) or just a much smaller scale con, and at the small scale event get a little acquainted with the crowds.
Your friends won't mind, if they did they wouldn't wait for you. they'll probably be happy to be off their feet for a while haha
You can do it, baby steps are encouraged