I started HRT 3 years ago on a low dose and 1.5 years ago on a proper dose. Even on the low dose I had some growth up to A/B cup. The growth seemed to pick up for a while after moving into the higher dose. So now I'm at a C cup, 36C to be specific. I used to think I was a 38C due to measuring but the band would ride up during the day so I had to drop a band. A good bra also will help give you more shape and profile than what you see when you are naked. I'm not saying you need a padded bra, though those can rule, but just that you should get a good bra.
The key thing to remember is that it takes a while and you should just be patient.
As far as BA goes, I know somebody that got hers back in 1991 and they never got hard or had any issues. Just saying it can happen though the trend does sound like most get a hard layer around it.
Another option that has some appeal is where they reuse some of your fat to pump the girls up. It doesn't do much beyond a single cup size and requires you to have the extra fat. I'd love to relocate fat from my middle to my micro booty and the girls. Maybe someday.