Breasts come in all shapes and sizes. The size and shape of your breasts are determined by the genetic traits that you inherit from your parents. The size is also determined by the amount of fatty tissues in the breasts. There is nothing you can do about what your breasts look like. No amount of exercise can increase your breast size.
Exercise works by building up the muscles, and there are no muscles in the breasts.
You also should know that breasts grow unevenly. One breast may become a bit bigger than the other breast. In fact, no one has two breasts that are exactly the same size, but usually this difference is not very noticeable. The shape of the nipple also varies a lot. Some women's nipples turn inwards.