I talked about this with some other friends today, and one of them had an interesting, equally relevant theory:
Maybe they weren't attracted to my femininity so much as I was attracted to women who like other women. Like a "gaydar" sort of situation. It does seem that homosexual people are able to pick up on subtle things, subconsciously, in their crushes and partners. So maybe I just saw a compatibility with them, as a woman, and they were only interested in me because I happened to be a decent 'guy' who they got along with, before they learned more about themselves.
Another unrelated thing of note: I have a pretty terrible long-term memory. Most of my early childhood that I remember is bad things. I can vividly picture the day my dog died, but nothing else from that time frame. I remember one time in elementary school where I saw one of the special needs kids drop her tray in the cafeteria, and I still feel bad for her these 18-ish years later. That's one of my only detailed memories from elementary school, and the rest are no better. But here's the thing: I can distinctly remember two things from my early, early childhood, possibly earlier than kindergarten: asking my cousin what it's like to be a girl and being disappointed that she couldn't somehow give a detailed description, and asking my mom (as if I needed permission) whether it was okay for me to go to the bathroom sitting down, just to see what it felt like. Those can probably both be chalked up to me just being curious as a child, but the fact that I remember both instances clearly and in a non-negative way must mean something.... right? The rest of my childhood is virtually blocked out in my mind.