First of all - don't panic. Your son still has a lot of time to regain some or most of those inches. Be as agressive as possible - meaning get the CAH under control so that the bone age doesn't advance any more and try to start him on growth hormones and possibly Lupron and Aromatase inhibitor.
Many people on this board have had their children grow for years without their bone age advancing. My son was advanced by several years at one point, and once he began treatment his bone age advanced very slowly and he caught up. His growth was a bit slow however but growth hormones could help there.
Just don't delay and try to get your doctor and insurance to prescribe growth hormones.
