The bra or no bra questions is as old as the chicken or egg question!
Welcome to the club of hurting breasts, I have this going on for over 3 years now, on gets so used to it, I am afraid I will miss something if it would stop! And the question for how long beasts will grow is also no exact science, and numbers between 2 to 5 years are floating around.
I don't know for how long mine will grow, because I had most of the growth already prior to starting HRT. But my body is slightly screwed up anyway. I take what I get, and hope it will no be more than a well filled C cup, but who knows?