It's very hard for me to gain weight. how do i get a cup size bigger in like a month or two?

Unrealistic desires.: The breasts enlarge naturally with weight gain, puberty, pregnancy and breast-feeding. Some oral contraceptives can be associated with increase in breast size in some women (sometimes). Building up pectoral muscles can lead to the breasts sitting on the chest wall in a manner that is attractive but will not increase cup size.