RE: not sure what to do
A boxer who is fighting, must find a comfortable weight, where it does not fluctute too much above or below, and maintain it.
If you try bulking up too 15 stone, you then have too maintain a certain amount of volume too keep the muscle intact.
Boxing is a sport of endurance, of conditioning.
If your body is not naturally sitting at 15 stone, adding all that weight in muscle and expecting to be functional in the ring sounds a bit unreal.
remember boxing is a skill, its an art, its not something where you go into the ring too look good.
Look at james toney, he doesnt look that great at 230 pounds, but hes as functional as it gets.
Boxings a great sport, but its not one for the bodybuilder.