My wife and I, who met in college, were good friends for a couple of years before things became more than that. I was rejected at least once or twice by her before that happened, though.

Same thing happened to my brother with his wife, and with my Dad. The males in our family are a persistent lot.

Since you're very young, I would suggest not pushing things too hard. If this person is such a good friend, make sure you stay in touch no matter what. Such a good friendship in itself is a good thing, as other posters have noted. If things are fated to go further, they will when the time is right. That's my opinion looking back on how things went for me.

Of course it also sounds like you are uncertain about a committed relationship yourself at the moment, which is also valid, no matter what your friends say. Always have to look out for yourself first.