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
Sherlock, Amy Pond, Molly Hooper, Shilo Wallace, River Song, Frigga
Captain Janeway, Idris, Kida, Sebastian Moran, Rogue, Horatio Caine, Katniss Everdeen
Ohayocon - January 2013
Otakon - August 2013??