I had a bone age scan when I was about 11/12 and they said my growth was up to 7 years behind the people my age.

i hit puberty about 16 and now at 22 I didn't develop under arm hair until about 17.   

my testicles are rather small and my penis is 1.5 inches when soft sometimes even small and I'm about 3 inches hard. The same as it was when I was 15.   

What should I do?