M.G.
That's a bit drastic, but if her doctor wasn't concerned, I wouldn't be. They're the expert. If you want to call - if you would feel better - then call them back, and get their thoughts.
Mine started out in the 90th percentiles. At puberty, they went down more to average. That was over several years. Sometimes their height would still be high, but weight was lower. Or vice versa. So long as they were healthy we had no concerns.