Because the deficiency was very slight, that is possibly why it was not picked up with the heel prick at birth.   At one point they could not even test with the heel prick for CAH at all, and in some cases it does not always pick this up as the child is found to have 17 OHP that is within the normal ranges. 

Even if your Paed is specialising in growth, sometimes they are more concerned with children that are not growing than children who grow to generous proportions.  Like I said also, your daughter, though tall may have been within acceptable ranges for her age group making it very difficult to pick up really until other body changes occur.  There are condtions that cause children to grow to fast besides CAH, such as gigantism, but the child would have had to have been growing out of what the medical field considers is the normal acceptable growth limits before they felt further tests were deemed necessary.  It is only when the child starts to show other visible outer signs of accelerated growth such as puberty, that it really clicks with a Doctor. 

There are a lot of grey areas and you may have had a Doctor that tested sooner, but 3 years is generally not unheard of for a child to be diagnosed with this.  2-3 yrs is the common age for later diagnosis and then later. 

I don’t think it is the Doctor’s fault that the child develops this condition in such a way.  The reality also is, that a child can be checked for height and weight in one appointment (depending how far that they were apart) and at the next appointment things have completely changed and  things have rapidly accelerated physically.  It is unfortunate, but it happens.  The only thing that you can do for the positive now is to consult an expert in that field, and they will stop the pubertal process and monitor your childs growth and do everything that they can to help her. 

You can always look at it another way too.  The child could have developed an illness and had a crisis when her CAH was not diagnosed and because they did not know what it was, much worse could have happened in that scenario.  It is good that they have finally got a diagnosis now as not only will they look after her in growth, but see to her health needs now also.  The asthma should be less of a problem with oral replacement with corticosteroids.