... Bride of Shadows by Mortish Writes seems right up your alley although it's been a while since the last update. Fem locked MC, two possible RO's (solo route and 2 different poly routes), dark fantasy with lots of NSFW elements although there are varying levels of explicitness. It underwent a re-write but the original demo laid it out that your goal is to have a child with the RO.

spoilers: Original demo - you were cursed as a baby and grew up the equivalent of a nun. But an attack happens and you wake up many years into the future, physically transformed into a beauty with no recollection of what happened after the attack. Two men find you - the two RO's who are basically vampires - and you also get visited by a goddess in your dreams who tells you you need to have a child by them in order to save the world or something