My daughter doesn't have the added complications, but she did fall off of her chart in height. She started at the 5th percentile and dropped to 0.1 percentile. She was only about 12 lbs and wore 6 month clothing at 1yr. It was pretty funny to see this baby about the size of a 6 month old walking and talking. She had a very extensive vocabulary for a 1 yr old.
I'm short and we just chalked it up to be my strong short genes. But, her ped. kept offering a referral to an endocrinologist. At 3, we finally took him up on it when her height had dropped to the 0.1 percentile. It turns out that she didn't have any growth hormone deficiencies, but was behind in growth plates in her wrist. They diagnosed her as small for gestational age and recommended growth hormone. She is now back up to the 5th percentile after 1.5 yrs of growth hormone shots. Once she started the shots, she started eating everything in sight. She grew stronger and was able to keep up with the other kids again.
A friend's dd also was small and they did many growth hormone tests before they finally found that she was defient in her insulin-like growth hormone. It isn't one that they look at as often (more rare to find) and she was not behind in growth plates, just very tiny. She is now catching up, too and is much stronger with a large appetite, too.
One other thing to check. We found this out at our ENT visit for my daughter's tonsils. They were huge and causing sleep apnea (snoring, too). But sleep apnea can be a cause for a child to slow on growth. They aren't getting the sleep cycles that they need in order to go through the growth patterns during sleep. Tonsils and adenoids could be something to look into. Does your daughter snore or stop breathing at night for a breath or two?
Wish you well and hope you can find the answers you need.
Oh, check the Magic Foundation, here is their website: www.magicfoundation.org
They have info. on growth issues and might be able to give you some information. There also might be someone with a child or family member that you can talk with that is experiences similar issues as your daughter.