Inescapable parent posse... yikes. I already commented earlier, but you never know. Maybe your parents will loosen up and let you kind of go on your own. Is there like a cousin you wouldn't mind going with that's older? What about the parental release slip?
I don't blame you for not wanting to cosplay in front of the folks. My mom asked me to dress up so she can get photos before I leave, and I'm kinda hesitant about it. I'm thrilled that she wants to since she's a little less understanding than my dad on the matter, but its still embarrassing.
Con goers are one thing, but folks are a different beast. It's up to you, Lo. We won't judge you either way. For sure. We'd all love to see you there, though. Maybe you can wow your folks since I'm sure so many people will want to take your picture.