I think it is important to keep a boy well supressed even with the weight gain that increased steroid causes so that those buds don’t get a chance to form any permanent kind of tissue.  My salt wasting son had the same thing happen.  He is now 17.  The doctors attempted to supress him better but increased steroid also led to more weight gain which also contributes to the appearance of breast tissue.  The doctors are not terrribly empathetic about the side effects as long as he is healthy, so we have always been on our own with these kinds of issues.  We finally got one doctor to admit, "yes, there are side effects to the medications but not taking them is not an alternative at this time."  It was actually a relief to have someone admit to the side effects so that we could finally just make a plan to help him deal with them.

He is insecure to this day about what clothes he wears and being shirtless in the summer.  The best solution we have ever come up with is lots of excercise, and controlled diet.  At 13 we quit driving him to the school bus (It is 1 mile walk each way) and took all TV and game toys out of his room so he would be forced into more active entertainment.   Other side effects we think the medications cause are joint weakness, sluggishness grumpy feelings, inability to concentrate, and eventually bowel problems due to a thinning of the walls of the intestinal tract. If I had known all of these effects and others in the beginning, I would have done things differently. My SWCAH daughter would have been in swimming instead of soccer, I would have carefully made sure that both CAH children ate food every time they took their steroid, and I would have entered my son in every kind of low impact active sport that I could in his younger years in spite of his low energy level.  Even with all of that they are happy and healthy and reasonably self-assured. You are doing the right thing to notice and look for a solution.  You are a good parent.