Peter

I feel like I ought to prefer "woman", because of the symmetry with "man" being preferable to "boy", but the fact is I do prefer "girl", and think of myself as a girl (although I'm not going to make a fuss about it in either direction), and tend to think of other female people my own age as girls.

But "woman" sounds less odd to me than it did, say, five years ago, so I imagine as I get older it'll gradually shift over and become the more natural term in my mind.