If I can add my two cents for a larger update for stomach capacity in the future:
- I feel the fullness mechanics from the minigames should be added to the dates and giving snacks, and have the level of fullness persist (at least partially)
- A girl's height and appetite should influence stomach capacity (i.e., a shorter girl can eat less than a taller girl)
- I've noticed that in the minigames, you can go above what's the maximum before ending, so maybe if you do that enough times it can increase her maximum by a little bit?