I'm probably the stupidest person in the world but: why is Left Hand of Darkness feminist? It doesn't have any female characters and it even has a society which doesn't have any women. Or is it enough that the writer is a woman?
Otherwise, excellent news! Congrats!
It has characters that are male or female depending on circumstances. (If you say that it doesn't have any female characters, you also have to argue that it doesn't have any male characters, either, except for Genly Ai, the male outsider). In effect, it gets rid of sex most of the time and then sees what happens to gender roles. One tenet of some kinds of feminism is that gender is socially constructed, not biological in the way that sex is; Le Guin describes this as her attempt to step beyond gender and see what happens.