I've played a few brothel management sims over time, but the one I was referring to specifically was "Black Market" (by E-Made+). The game does have some more... unsavoury parts to it though (which you can just not engage with). Not sure how explicit you want your game to be, since so far it is on a more vanilla and tame side.
Another game that comes to mind is "Monster Black Market" (by Team-Apple Pie).
I don't know what the etiquette here is on itch in terms of talking about NSFW stuff or links etc (actually made an account just to comment on your game), so I'll refrain from posting links here just in case.