Please, do not worry so much about the actual numbers of her height and weight. Those numbers mean very little in the larger scheme of things. I went through the same thing with my son...only worse. He ate like a hog but only really gained weight once I started him on solid foods. Long story short, he was about 12 lbs at 10 mos...Inasmuch as the Drs. were throwing a fit (and yes, some yahoo decided they had to call CPS), Tristen was gaining and doubled his weight exactly when I thought he was going to; he was just slower to start. If your daughter is generally happy-go-lucky and hitting other developmental milestones, do not worry so much. Children and adults always lose a little weight when they're sick and eating habits change and as long as it does not go on for a few months in a row, she is fine.
Do try to feed her as much formula as you can before she starts to gag. That will give her the extra nutrition that the other foods that she cannot get down are not giving her. If she can only take one oz. before she starts to get sick, that's fine start giving her pedialyte (your lucky, mine won't drink the stuff!). As another woman said, start her on the blandest BRAT foods bananas, rice, apples, toast....do not put anything on the rice or toast i.e. butter - nothing! Cheerios are OK too because they are soo plain, they act like the toast.
Take care, you are doing perfect by your daughter!
M. M.