FYI, I am sitting here reliving (with happy nostalgia) various of our now-long-ago conversations about how Willow/Tara isn't slash, Buffy/Faith is slash, and Buffy/Spike (at least pre-S6) is also slash, or at least could be, even though of course that wasn't the label for it within the fic-reading and -writing communities I knew about.

I have jumbled thoughts about the differences between homosexual (or homoerotic or gay or for that matter lesbian) and queer, and how queer actually seems to me to have more overlap with slash, for various reasons; and also about how much I loathe the term "femslash," for reasons that relate to your original post (it reifies m/m slash as "real" slash in much the way "slash" reifies het as the norm). But grading has numbed my brain to the point that the thoughts aren't coming unjumbled, so I'll stop there.