My son’s bone-age has always been very delayed too, although this has caught up a bit in recent years.  (At the age of 12,he had the bone age of a 6 year old!) I think the ambiguous genitalia is a strong indication of CAH, although there are of course other causes for this.  I imagine there must have been other factors for S/W CAH to be diagnosed though.  Apart from the initial high 17OHP level which was taken at 15 days of age (as he wasn’t diagnosed until then) my son did not have another raised level too - until recently.  I assume your daughter was treated on hydrocortisone since birth, so her 17OHP level may not have been elevated.   Although your specialist could arrange synacthen tests, they are not particularly pleasant as the child has to come off all medication and be hospitalised.  In my son’s case even these did not confirm CAH though and actually still indicated he did not have the condition.  DNA confirmed CAH - although this test can take a few months.  I now know of 8 other families who have been through the same thing - where diagnosis due to undetectable levels of 17OHP has been in doubt but  CAH was eventually confirmed in all cases.  I know how upset and frustrated you must be, the waiting and not knowing being very difficult to cope with.  Ask if the DNA testing can be treated as ’urgent’ as you are very distressed - they owe you that much!  Phenotype does not always match genotype and there is still a good chance that the CAH diagnosis is correct.

Bone ages are not normally performed until 2-3 years of age as they are unreliable before then, so in this respect your daughters consultant was not negligent.