That's the only way to write. Sometimes I write something I know (or at least think!) will be wildly unpopular, but if it's something I have to work out or express for myself, then good enough. It can be very frustrating not to get the response you're hoping for ... but as you write more different kinds of fic that may get different kinds of response, that tends to get easier. Have you put your AU on AO3? Sometimes you find a different audience there.