By the way, are you going to add height potions, lactation potions (Another way of gaining milk), and multibreasts potions? Will there be a feature to increase (or remove) the cap for body parts or possibly as an option? And one more thing, will you be able to gain a (Possibly permanent) buff upon using certain potions? EX: Like using a Fitness potion increase your speed and how long you can run?
Regarding the size changing potions: it's very complicated, both technically and from a game design perspective. Just think about it: entering buildings, syncing sex animations - all of that is tied to character size. I do have a few ideas about it, and I personally really want to see it in the game, but I'll be straight with everyone - I have no damn idea when I'll be able to implement it.
As for everything else : it's already in development. For example, right now I'm working on the combat system. Buffs from potions could follow right after that, since they're logically connected.