In my medical recorts, my doctor wrote this about me:

"Rick's growth and bone development have been affected by his high steroid use.  He was evaluated completely in the Pediatric Endocrinology clinic at the children's hospital.  Their findings indicate Rick is constitutionally delayed in growth and his severe asthma and requirements for high-dose steroids over the past several years have contributed to this delay.  Based on their information, Rick has an estimated adult height of 5 feet 6 inches. Rick also has steroid induced osteoporosis that needs to be dealt with. "

Being the worrying type I was back then, this news caused me much anxiety.  Yet my counselor assured me this was nothing to fret about.  He said, "Doctor estimations are nothing to worry about. Your main concern right now should be getting your asthma under control and the steroids are helping you with that."  

A few months after I was discharged from the asthma hospital, and completely weaned off oral GCs but still on high doses of inhaled ones (4 puffs 4 times a day of Azmacort), my doctor told me I no longer had osteoporosis. But my height continued to vex me.  Even as a senior in high school I had the body of a freshman.

Despite those NJH estimatinons, however, I am now 5 feet 8 inches tall.   Sure all four of my brothers are taller than me, but who cares.  My current height works just great for me.  If the GC shrunk me 1.1 cm, I can't tell and don't really care.

My advice to you is the same as that given to me by my counselor back in 1985:  "It's better to let your doctor do what it takes to treat your asthma now than to risk worse asthma -- or even death -- down the road, even if that includes steroids."