Hi Julia
I started lowish dose HRT 5 months ago. I am 45, and am surprised to see more growth than I expected, but then, I wasn't really watching out for the changes, deliberately, and things just kind-of popped up!
My advice is to forget about your breasts and get on with life and with being a girl (or a girl in training!)

After 3 months or so, get your homone levels checked regardless to ensure that yours are in acceptable ranges.
Hormones are no magic potion, Obelix.

If your dosage is right, small but wonderful mental and physical changes will happen, very gradually....
Hugs
Julia