Hi Anna,
I have been on HRT over 2 years. All of my HRT meds are in pill form. I have been on estradiol and spirolactone for two years and 2 months. I have been on micronized progesterone for 4 months. In two years I've gone from flat-chested to A-cups. I am currently in between sizes. Eventually they will round out to B-cups.
I was told that whatever size breasts of the women in your family you can only hope to achieve a cup size smaller. For example both my sister and mother ended up with C-cups prior to being pregnant so the largest I can achieve would be a B-cup. I wish I had C-cups but if I can at least achieve a B-cup without breast enhancement surgery then I'll be happy with that. Implants are not an option for me.
Its too bad that bras aren't made in odd sizes, only even sizes. Because of my shoulders, my ribcage and my breast size I would currently be considered a 37 A-cup. I normally wear a 36 B pushup bra. It fits me just fine. My last significant amount of breast growth was within the last 8 months. My breast growth has been occurring much more slowly since I've been on the progesterone. No doubt its been maturing my breasts.