Mine hurt when they are growing. Well, tender anyway. Mine have been hurting and growing for, um, 7 months constantly. I'm three years into HRT. I've had periods where they didn't grow as much (or maybe not at all) and they didn't hurt. So, you can get times where they are growing, even for 9 months, and then times when they aren't. Even if they don't hurt, or are tender, they can still be growing or filling out.