Breasts are increased by getting her pregnant once. She'll start lactating. Or you can (didn't test it) have sex with her nipples and her breasts will store the cum. After the night is over you can select to turn discharge on or off. If you have the discharge set to on, stored up cum / milk will slowly drain out. If you leave it as off (which is the default) her body will keep expanding (to a degree).
I think the issue of multiple births every night is that fetal growth rate and/or increased fertility has a bug. I tried to simply not have sex with her, ie drain her dry. Except she kept getting magically getting pregnant. I gave up on that when she had 200 children waiting to be born.
Animations aren't bad, but it clearly lacks polish and is missing some features that you typically see in many sleeping girl games.
If you want to break the game at comical speeds, spend RP to decrease ease of wakening to 0.1 and buy sensory depravation ability. Doesn't matter how easy you set her to wake up, you have to work at it to make her wake up after that. That will only cost you 14 RP. Just remember to turn the depravation on before you go to night time or she'll wake up like normal.