It should be noted you can also increase the girls' wombs to 3 size with consumables. I'm not sure which ones exactly, but all the consumables can buff and give any of the girls just about any of the general skills and improvements that the special girls can have. So later on even buying girls with horrible negative general skills isn't a big deal. You can just spam them with milk and fix those issues.
One of my biggest pet peeves in this game is the consumable lady's quests kind of requiring you to play bad to get her H scene. You have to intentionally let your girls get STDs to create cures for them, that feels pretty bad. Another thing is that women don't really benefit much from breeding with monsters. I know milk can fix that and they can create offspring with normal humans to buff their abilities further, but it still feels a bit weird. Female monsters and male humans certainly would have been preferred over the milk buffs. That's one thing keeping me from considering it a decent "breeding season" game. People applauding them for having all the characters compatible are missing that point.
Did some testing and the success chance seems pretty low, but here are some I've confirmed for milk consumable buffs:
I'd guess the small furry milk would give womb size increases since that's one of their racials. I don't have enough stocked up to test it too well atm though. All the milks seem to give general bonuses that are most common for those races basically. Offspring from human partners also seems extremely likely to birth girls with 3 size wombs as well, so that's an even more reliable way to get an army of them. Almost all of my nekos and dragonian children have 3 size wombs.