Oh Aslyn, that's awful about the teasing!
This is an interesting thread. My DD is 15, and still has no interest in boys. And when I've asked her, she says she's not interested in girls either. And she hit menarche 5 years ago. But she does have some vague interest in sex-related stuff. I know she reads yaoi fan fiction stories. (Yaoi is easiest to describe as Japanese light homoerotica marketed to girls.) But she still freaks out about kissing in movies and books.
I'm sure having a step-dad contributes to this. She's also very introverted and not all that interested in people in general. Last night (a Saturday) found her watching her math class (online), with no notion that there was anything unusual about that. She has an old friend from elementary school that she goes out with once or twice a year, but that's about it. She's now involved in a school play (she goes to school part-time), and has joined a group organizing some sort of Earth Day event, but otherwise, she's a total homebody.
As for me, I was interested in boys from at least age 6, having some pretty significant crushes along the way. And I didn't even hit menarche until nearly 14. I perhaps was looking for more male attention, as my parents' marriage was less-than-ideal (and my dad was away lots b/c he's a trucker), then he left when I was 11. But I never actually had a real boyfriend until I was in Gr. 11/12, and I've only dated 4 guys total, including both my current and my ex-husband. I think my acne protected me from a lot of things.
My friend, on the other hand, her daughter became her son when he was 13. And it was a pretty obvious thing, since from toddlerhood, everyone who met them thought this child was a boy until they were told the child was female. Now, unless they're told directly, no one knows he was ever anything but a boy.
Overall, I wouldn't sweat it at 9. Being gay can mean a more challenging life in many ways (and not something I would wish on my children), but you're fine with it either way, so it'll all turn out fine in the end. It does certainly sound like your DD is not an average kid (this is a good thing!), and that will create some challenges for her with her peers over the next few years, but that's a completely separate issue.