Who are you to say she isn't gay? No one needs to have some traumatic experience happen to them to think they're a homosexual. Many homosexuals have lived decent lives, I'm sure. And no, it's not always a phase. If she feels that's who she is, then that is who she is. And unless you're a girl who's been with other females, I don't see how you can say she won't be happy with another girl if that's what she truly wants.
I understand how you feel. I have trouble meeting other gay girls that are my type with similar interest as me. All the girls I meet are either too girly, straight, and dating, or just really not what I'm looking for. Sometimes I fall for guys, but that never works out either, and I'm not too attracted to them either. Wish I could offer some help.