Children's weight and heights are compared to a Growth chart which is a range per age. From your measurements her weight is below the 5th percentile and her height is on the 5th percentile for her age. She is below the growth chart range which indicated she could be underweight or small for her age. If her weight has been steadily increasing (slowly), since an infant, then she has is just small for her age. If that is not the case, then she is underweight. Suggest making yogurt smoothies or milkshakes - yogurt, milk, and frozen fruit blended together; or milk, ice cream, and frozen fruit blended together. Give her the milkshakes or smoothies at every meal and snack in place of milk for extra calories, protein and nutrients to help increase her weight. Some tips for additional calories: If she likes pasta, then add meat or cream sauces to the pasta instead of plain tomato sauce or plain pasta. Add dry milk to oatmeal, mashed potatoes, gravies, creamed vegetables, and creamed soups (add additional meats to soups). Hope this helped you.