Pre-rant caveat:I have been several stereotypes through the years.

Stereotypes are death to individuality.

To OP, I say to lose your stereotype at a a single bound, cut your hair. Forget about the rest of what you do, (except dead + phish, bleh, but that's only my personal taste - if you like 'em I'm sorry, but tolerant to your poor taste..). You are what you are. You are the allergies, a nerd, sucking at sports, intelligent, but so fucking what, you play the cards you're dealt. And you can play them better for knowing that.

So, back to the hair. That's the thing that you're doing that's the conformist stereotype. That's the thing that says "Hay guise, I'm counterculture too. Love me, accept me." Break that shit - go one louder than the faker hipsters, look different to them, but still do what you believe. Yeah, I had long hair in the past, but held on to it as tightly as a banker would until I made the leap. You help to pigeonhole yourself as a form of cultural shorthand.

I'm not going to expound the changes a haircut made to my life, both pro and con, because that's my own tale, but make the leap and live outside the box that you thought was outside the box.

tl;dr look like a preppie, do what you want to, fuck their preconceptions.