my baby is not becoming chubby what shoyld i do

A. don't worry If baby is active, playful then no need to worry for weight.  Baby gain weight 200 gms per week for first 3months of age  Baby doubles of it's birth weight  at 5.5 months of age and triple at 1yrs of age. At 1yr weight should be 9-11 kg  At 2yr 10-12 kg  And at  3 yrs 13-15 kg  4yrs 15-17kg  5yrs 16-18kg