Perhaps this is one of those typical questions that shouldn't be asked to us lay-people, but to a proper endocrinologist

Having said that, there is anecdotal evidence of desensitization. These are people like us though, who, for better or for worse, have seen their breast growth stalling before the desired result. Whatever. People are inclined to see dragons and monsters where simple solutions exist.
Go and ask your doc, I'm sure there are answers out there. What I do know, is that the human body is a very, VERY complex system and it works differently for each and everyone for us.