I like the potions in the item shop, but the selection is really limited. I was thinking of some that could be added at a later date:

Lactation potion: Drink it while thinking of someone and they will lactate for a short amount of time (drinking more than 2 for the same person makes it permanent) (Usable on Protagonist)

Breast Expansion Potion: Exactly as it sounds, each dose makes boobs permanently grow by 1 cup size, use on slaves in bedroom  (usable on Protagonist)

Futa potion

Fertility potion

Just a few things I thought would make the game more fun.