Thanks for the chapter!
While stimulation can help the two main things for growing breasts is genetics, rest and proper nutrition. After all, can't grow if don't have the blueprints, body impaired or being damaged due to too much activity without rest, although too much rest is bad in different ways than too little. Also, need the right materials to grow which are severely lacking in junk food, and too much adds flab all around and too little means an incomplete job. Would've been funnier if the vampire and succubus put their two cents in too.