Talk to the alien leader!
I talked to the alien leader and it still only has two options one for growing mega boobs on yourself and leave option
Ask Bell to grow boobs and choose the mega option.
it keep saying although you can change them bell won't keep them unless you find some way to offset the increased weight of her boobs and and when I tried to ask her the only options are talking about aliens and then bell's signal and bell milk
check around the holding cells of the alien ship, you can start there
