Breast size. Likely to ^ w puberty, pregnancy, breast feeding & possibly prior to your period. You can build up chest muscles w exercise & weight lifting but it will not ^ the amt. Of fatty tissue. There are no pills, herbs or machines that will ^ breast size. Breast augmentation is surgical enlargement. A padded bra will ^ appearance of volume. A supportive, well fitting bra can also enhance appearance.
Not really possible. Breasts will change with pregnancy, but you can't actually increase your breast size with medication or exercise (you can increase the muscles under the breast, but not the breast tissue itself). It's more important to learn to accept yourself as you are, that you are beautiful just the way you are.