Lolita there are so many thoughts your post evokes for me!
What bothers me most, though, I suppose, is the way your lesbian acquaintance assumed that as long as you were a lesbian it was okay to be so biased and, as you say, heterophobic. It's as bad as when white people assume as long as they're around white people it's okay to tell racist jokes, or that it's okay for men to talk trash about women as long as there isn't a woman in the room.
I'm also struck by the anger I feel when I read your words about not being recognized as bisexual. I face the same assumptions and have generally shoved the anger down and avoided experiencing it, but there is, really, a terrible feeling about being made so invisible. And while I would hate to make the category seem more "categorical" than it really is, it pisses me off to be seen incorrectly so much of the time.
Now, I'd love to know how you came to choose that particular photo! It's wonderful.
...because public space really matters!
Elizabeth