Hullo,
ive got the same problem, ive only just started taking any action about it thought.. Ill sum up what I found out..

If you dont pull your foreskin back bit by bit as youre going through your teens, then when you get to 18 it may not be able to be retracted fully. This is the problem I have, I can retract it sometimes, but its tight, and if I do it too much it gets sore and wont retract at all. Basically, I read some stuff on the web about it and the best thing to try first is natural stretching, like pulling it to where its comfortable then leaving it for 5 mins every day, and pulling it back as far as is comfy when you pee, etc. But dont do it so it hurts, this will only damage it. Give it a try, see what happens, it also recommends that you make your penis warm before doing these exercises.
hope this is of some help, anything you may want to ask ill try to answer ..

Cheers
m

Why do you want to have unprotected sex? Are you in a stable relationship? Have you and your girl both been tested? Stds are a very serious thing that alot of teens have!! You need to protect yourself. Plus do you want a child? Is she on b.C pills? Pulling out is not a method of b.C. You can very easily get pregnant by doing this.