If doctors and tests and her gait say her hip is fine, then probably her hip is fine. I have had noisy knees all my life and it probably has contributed to my old-age osteoarthritis ( I'm 60- btw), but it didn't hurt me a bit. My 26 year old son has very lax joints, which crack all the time, but he functions normally. I think we sometimes over-analyze as concerned mothers, and the modern-day trend to perform medical tests at the first sneeze doesn't help. You did the proper things by consulting a physician, and you had some testing done. You can rest easy knowing that her history will have that recorded for future reference and that you took the necessary steps.