my baby born with 3kg and now she's 7 and half month old with 6.4kg I think this is low weight gain what can I do with her weight

A. Wi-if I only go by the birth weight of your child your child is having a good only hundred grams behind the expected whereas it should be 6 1/2 by completing the time of seven months so the weight gain is very much appropriate as per the birth weight of your child