Daniellekai,
About 2 years ago, before HRT, I was also overweight. I had moobs that went their own way. Not to worry.
Now with 2 years of HRT, my chest is definitely much bigger.
Yes, with HRT you will develop breasts similar to other women in your family. Genetics are just as important as HRT.
I really do not think that wearing a bra to reshape your breasts will be successful. If you have any changes, I would expect minimal changes.
Bras are for support. Wear one when you feel the need, either physical or emotional.