5'1, 100 lbs. Over the muscle 250cc high profile implant to under the muscle; what are my options?

I am sorry to hear about your concerns after breast augmentation surgery. When it comes to revisionary breast surgery, it is extremely important to make the correct diagnosis, in order to formulate a surgical plan to improve the patient's specific "problem".In your case, given your description of "very firm", I would be concerned that capsular contraction is present. If this is the case, conversion to the sub muscular pocket plus/minus any additional maneuvers (such as breast lifting) will likely be in your best interests. You may benefit from consultation with additional board-certified plastic surgeons who can demonstrate significant experience helping patients with revisionary breast surgery. Best wishes.

If you know how to loosen the muscle properly going from over to under should not give you a double bubble if you don't have one now. I think a 150 hp implant would look kind of round. If you want to look more natural a lower profile implant is often better in that size range. If they are firm you may have a bit of capsular contracture that is making them look round