I just went to my first and I'm super shy too. I nearly had a heart attack when a friend convinced me to get up and sing "Infected" in my Shilo costume in front of the entire Repo panel. o_O
But at any rate, I've been cosplaying for years without going to cons. I love just being able to personify my favorite characters, whether it's while acting something out or taking pictures with my friends, or even when I was little, just running around in the corn fields in my Star Trek uniform pretending I was Captain Janeway on an alien planet. I think that as long as you're having fun, it doesn't matter!
And you could always have a mini-con/costume party with a couple friends sometime if you wanted a manageable group atmosphere.
I hope I've said something vaguely helpful and not just rambled on lol