Hi. Your mod seems to mess with the third quest. It's impossible to complete the taurus quest. And if I remember correctly (not sure), in the vanilla ver. you don't even have to grow more tits if you don't play with the option activated for furry.
Viewing post in Aric's Expansion Rebred
Pallington is correct, it seems your game is either not installed correctly or may be interfered with by another mod. You do have to grow additional tits + develop them. The idea behind the quest (to my understanding) is meant as an introduction to nudge you towards the laboratory.
Edit: I didn’t make any changes to the quest reqs beyond allowing it to accept higher sizes, but perhaps in an older strive version the furry settings would disable that. I can’t recall ever seeing that though