Hi Namaste,
I'm a bit like yourself. Prior to HRT I was on herbals for 18 months and developed a small set of B's. After 8 weeks of HRT so far, those small B's have filled out all the wrinkles in the cup and I'm still getting growth pains. Buds are still yet to develop fully. So I suspect you are in for more growth.
What size was your mother, and any other female siblings, if any, in your family? You may have to stick to the motorcycle jacket, as once you really get past a B cup there is too much volume in the breast to respectfully contain it with the use of sports or minimiser bras. No self respecting shirt could hide such volume.
In all seriousness, if they become excessive, you do have the option of breast reduction surgery. You may need to evaluate that after about two years HRT.
Keep in touch and let us know how you are coping.
Be safe, well and happy
Lotsa huggs
Catherine