hello my 22 months old looks lean.... though she eats all healthy homemade foods n also she eats pretty well never ever I had a problem wid her food she eats evrytng watevr I give but still not gaining enough weight she's a preterm baby wid birth weight of 1.5kgs n now she weighs around 9kgs n also her height is 83 cm....kindly suggest wat can b d reason??