gigantomastia
A medical term for natrual drastic enlargement of the breast. It could happen during puberty (virginal) or pregnancy (gestational)
(Virginal gigantomastia) A teenager going from an A cup to a DD cup in two weeks
(Gestational gigantomastia) A woman going from a C cup to a G cup
(Gestational gigantomastia) A woman going from a C cup to a G cup