Besides the other replies, it's important to know that Chromium based browsers (Chrome, Edge, Vivaldi, etc.) share the limited storage space between all web pages. So if you play a few html games the storage is full quickly. As mentioned it just around 10MB, some games can fill that up fast (Free Cities).
Firefox based browser keep the storage for websites separately, so the 10MB limit goes for each website without interfering with each other. So if you have trouble with no space and don't want to delete save games, then I recommend switching to a Firefox based browser.
In the QSP version, you need to go to the Monastery in the mountain. I don't remember if you need to talk to the Witch in the Woods about it first or if you can go straight there. You can buy the demon cum needed in Mont Creek or from the Magician in Solomn's circus.
In the Twine version, I think the kitsune in the mountain are the ones you have to talk to. I've played that less, so I'm less sure on that. I'm also not sure where a chaste PC would get demon cum since I got mine straight from the source in Hell
Bug?: In the Twine version, I think I had 4 ratfolk children at the same time. I say think because for the duration of the pregnancy, I only had a "$womb" on my character so I'm just assuming they came as a package deal. I only got to name one of them and only became aware of the other three when I checked "View Children" in bed