Your breast size is determined by genetics. People say us T-girls are normally one cup size smaller than the women in your family.. having said that...
All the women in my family are big breasted, I am talking DD and DDD etc, My mother is the smallest with D's. HRT has given me D's cups as well, I actually wear a bigger bra than my mother, she wears a 34D and I wear a 36D.
I love my breasts and would not trade them for anything. The larger Cup size requires me to wear a good bra and i have learned to appreciate a good bra. A good sports bra is a requirement when I exercise. My girls get a break at night, as I dont sleep with a bra on, although some on my sexier nighties do offer breast support. My mother and room mate told me its not good for them. Sleeping, well I sleep on my side, that was something i had to get use to, because I was a tummy sleeper before.
Remember again breasts come in all sizes and shapes and women are never happy with them.