On average, infants gain about 1 kilogram per month for the first 3 months, ½ kilogram per month from 3-6 months of age, 1/3 kilogram per month from 6-9 months of age and ¼ kilogram per month from 9-12 months of age. Full term infants double their birth weight by 4 months of age and triple it by 12 months of age.
She should approximately triple her birth weight. She has doubled it at this point. Seems like she is doing well.