How short is too short?

This is something I’ve been debating, as I work on short erotic pieces to put up for publication. I’ve had slow but steady sales of my first two short stories, evenly distributed between them. I had one comment on an Amazon review that my “Bitch Brigade” is on the short side, and it really is, at only about 2000 words. I have two more shorts that are ready to be published, but one of them I think I’ll wait until it has a companion. It’s a gay erotic piece with a touch of domination/submission, but again it’s only about 2100 words because I’d originally written it for some of the magazines out there, which prefer short pieces. The other one is a nice 5400 words, lesbian erotica, so once I’m done getting the edits and beta readers’ comments, I’ll publish that baby.

So I’d love some comments. For erotica, what is your preferred length for short pieces? Thoughts?