It takes place on another planet, and isn't alien biology "science" speculation, enough?

Besides, it's not even her best work.

Looking forward to reading your story! You might consider Ted Chiang.

Having something like another planet or alien biology is necessary but not sufficient to make something science fiction. There is some fuzzy amount of focus on science/technology, style, and tropes that are needed to make something more science fiction than fantasy or speculative fiction. The Left Hand of Darkness read more like fantasy to me, and I don't think it would have been any different at all if the setting was Middle Earth and the ambisexual species were Hobbits. I think I wouldn't have blinked if it had been described as "science fantasy" to me rather than "science fiction".

I'll bump up Chiang on my reading list, I have heard a lot of good things!