I'd say that's definitely part of the same problem: you don't fit people's narrow idea of what a heterosexual woman is, thus you can't be one! Meanwhile I apparently do fit people's expectations of Straighty Mcstraight person and so they have trouble getting their head around me being attracted to women.

It sucks that people are like that. And yeah, I'd be fine identifying as bisexual if I was but I'm not. Though I imagine being associated with the stereotypes around bisexuality is pretty annoying for those who do identify as bi too.