I think many 'grown ups' worry about being labled and judged in many ways like 'nerd' and 'loser'. But I think those words have particular meaning for you and I think you have already decided they apply because (? - fill in the blank: because of your interests, personal achievements, etc?).

I think maybe you judge yourself this way and you fear others will too because you do, as if others don't have their own thoughts about you.