14 months old baby girl and weight is 7k

Hi, My daughter is 14 months old and is 7kgs. Her birth weight is 2.8kgs. She is very active but does not eat much. She is walking on her own and started talking too and does what ever we do immediately and is very sharp at observing things. Our only concern is she is under weight. Her diet is morning she eats idly or upma as breakfast and kichidi with veggies for lunch and dinner. She does not like to eat fruits but i will manage to feed her atleast small qty. In between she drinks buffalo milk 3 times a day some 100ml each time. Please suggest us something to improve her weight and also is this weight normal or is there anything to worry. We as parents are very confident that baby is doing perfectly fine but relatives and neighbors are saying she is very small and weak. We are very much worried whenever someone says this to us. Please help out Thanks