I would suggest you to make your child eat food every hour or in 30 mins if she eats very small meals. It is very important to fulfill her nutritious needs for better growth. Make her eat at least 1300- 1500 kcal per day as per her growth requirement by completing the required amount of carbs (105-110 gms), proteins (12-14 gms), good fat (30-35 gms), calcium, vitamins A, B,B6, B12,C, D,E, K and minerals, iron, riboflavin etc so that it also helps her gain weight. Also make her do maximum of physical activity the whole day. If you want I can help you initially with a week long diet chart
. Please help me with some food list she likes.