Bonnie, The doctor told me when the testes reach 4mms, that is when a boy is on the verge of puberty. At that time my son was only on the 10th percentile for his age, so quite small but he is now 5ft 8" and I am told he still has some growth left (at 18).  His father is only 5ft 9" and I am only 5ft 4", so he is well within his genetic height potential.  I understand your concern but think you are probably worrying a little prematurely as there is a very good chance your son will reach his full height potential, especially as he is only a carrier of CAH.  You can always introduce growth hormone or aromatase inhibitors in a couple of years if growth hasn’t taken off by then, but I doubt they will be necessary. Here’s hoping......!