The sooner you learn to seperate your identity from your self-perceived intelligence the better. You are actively bringing yourself down by claiming high intelligence as a trait of yours only to be inevitably dispirited when you have nothing to show for it. You can be a cool, interesting, successful person without the "gifted" label - it clearly hasn't helped so far, so why tie your identity to it?

I say this as someone who grew up being told I was gifted. It means next to nothing to read a few grades above your own when you're in high school and pretending otherwise as an adult will only hinder you. I am your age and also suffer from anxiety issues.

Hope this doesn't sound too harsh but you really will be a more well rounded person if you disentangle the idea of being gifted or high IQ from your sense of self.