It almost doesn't even matter what you call it anymore, except a publisher will want to know because if you don't even know, the publisher isn't going to give you the time of day. If you go to the bookstore, it's probably going to be lumped in with either general fiction or Syfy/Fantasy anyway. So, either/or, pick one. If it's not a romance or western, the categories are getting narrower and narrower, or I should say broader and broader to the point where soon there may eventually only be two. Fiction and non-fiction. Then again, by then there may not be many, if any bookstores left to worry about it anyway.
On line, maybe it still may matter.
I classify my stories based on what I want to call them. My horror, which I call "icky bug" is about monsters and mayhem and some may call science fiction or supernatural thriller. I don't really care. To me, it's b-movie horror...icky bug even though there aren't any actual bugs involved. It's just a term I coined decades ago. My fantasy stuff is fantasy. My adventures are "adventure/thrillers" now. YOU need to figure out what it is and stick with it, whatever it is. Write it, then decide.