My hair's about the same length - perhaps an inch or so longer.
I'm growing mine out, so I'm keeping it long, I'd say if your goal is the same, then dont' cut it. You ARE a 17 yr old punk kid, right? Fuck, enjoy it while it lasts.
I'm 25, and thankfully, I'm in a profession where people judge me by what I produce and not what I look like. (I also have tattoos on my forearm, and usually wear t-shirts to work - gotta love the TV/Film industry). Being a man is a matter of what you DO and DONT do, not a matter of appearances, so wear your hair however you want, and don't take no shit from anyone telling you it's too long - it's not too long until YOU think it's too long.