Thank you for coming back and giving an update! I am glad your son recovered from the steroid doses... sadly the docs don't realize the consequences of the inhalers.
It does pay to be persistent!
An update, my son is doing so much better. They did give a physiologic dose of cortisol after 2 adrenal crises that sent us inpatient. I found a more compassionate endo who reassured us that we were on the right track but that it would take a looong time to recover. They determined the cause was the inhaled corticosteroid(Advair in this case.) After we stopped it, he began to slowly get better. After one year he still was not feeling well on a daily basis. He started to grow, still not feeling better and finally now 22 months after the emergency appendectomy and 20 months after this post, 20 months after stopping the Advair he seemingly is back to normal! I advocate for all parents to trust your gut and get a second opinion even if it offends someone. Find out as much as you can about this issue! You are the person most knowledgeable about your child and the one who cares the most for them!
I am so sorry for your son...
I would contact the magic foundation and find a good endo that specializes in all growth issues - it may or may not be just IGF-1 but something genetic or some other pituitary issue.
That being said, cortisol can be an issue as well. So I would hunt down a doc who has more ideas! You need a neuro-endo who has the expertise to find the right skills to get the testing he needs.
Hang on in there i feel like you could be talking about my son,everything is the same even down to the appendectomy.Its been a long hard road but hopefully i will get answers to day that i can share with you.