Just a thought: put your game on steam! Another lewd game, Corruption of Champions II recently put their game on steam and the sales were through the roof!
Fair, though Early Access would be a viable choice.
I really like this game and wish it to succeed more. It's doing well, but it seems to have too little internet presence, despite the fact that (imo) inferior games are more well-known than MGD.
Being on steam and being more active on twitter should help quite a lot