Sounds like you're doing everything correctly then, but there just isn't a market for what you're writing. It's a reality all writers have to face eventually. It doesn't matter how perfectly you execute a story if nobody wants to read that particular story, or that particular execution.
(Assuming you want an audience, and don't just write for yourself, of course.)
The reason you aren't liking any of the advice you're getting is because: there is no advice to give. You're already doing everything you can, but there simply is not an audience. You can't squeeze blood from a rock. There are no more (or inconsequentially few) readers who are seeking million word Ranma fics with your premise/style/etc.
And from that factual reality, you're getting advice like: make fundamental changes, write something else, etc. Which you don't want to do. Which is fine.