I'm sorry you had a rough time with this. You didn't do anything wrong and you have nothing to be ashamed of.
On the other hand, I really don't think your friends did anything wrong either. Reasonable minds can differ on this point. In my opinion, they were the sort of good natured fun that friends should be able to share with one another. This time it's your breasts, maybe next time it's Marc's bald head, and after that Tracy's tendency to date stupid men without a job.
Having a sense of humor about all this is OK.