Fun fact: Zoey's sprite artist messed up her breast size ages ago by making them H-Cups when they were supposed to be DD-Cups. My producer and I tried to get him to shrink them, but he didn't really understand what we were asking (he's Indonesia, and while he knows English, it's maybe fair to say that he doesn't fully understand it at times) and made them even larger in one revision, and we ran out of revisions and patience.
I do agree that they're a bit too big, but this game takes a detailed look at what the logistical issues involved with someone suddenly changing the sex of their body and having to hide it and a sort of "buyer's remorse" for Zach to a degree as he might have thought about being a woman but not the consequences of being one, and the breasts being so big draws attention to both.