Don't be too hard on yourself, doll. Everyone is different, and no one, but no one, can predict what will or will not happen for you. Just have faith in the process, take your meds like a good girl, and work on falling in love with yourself everyday... that's what's really important here.
I have a (cis) step daughter who struggles with the fact that she has one small but well developed breast, and one small obviously underdeveloped breast. These things happen. They just happen. Not to suggest that such a thing might happen to you, but rather that worry will gain you nothing, and relaxing into the process will yield you infinite rewards in peace and well being.
I was told early in transition by a lovely trans woman friend who transitioned early in the 70's that I should not worry myself too much about breast development. Like any girl going through puberty I needed to be patient and to give it time. She suggested that breast augmentation surgery is always an option, but she very strongly suggested that I give HRT at least 5 years to do its work. That's about how long puberty takes to do the bulk of its body work.
I took her suggestion to heart. I waited 8 years. My body, mind and social standing shifted, changed and evolved substantially during those years. And eventually when I got breast surgery, I knew what I had to work with, and I knew what I wanted.
Seriously, do what you can to fall in love with yourself everyday. It will make everything about transition flow so much easier, and self-love will enhance your natural beauty in ways that you can't even imagine.
You go girl!