Talk to Pediatrician on 3 Months Old Baby, Not Gaining Weight

My baby is 3 months old and his Weight is 3 kgs.. He was born through C section and was born a few days before EDD because my BP was remaining high. At birth he had RDS and Jaundice both got away with treatment eventually. He is all good except that he has colic problem and is not gaining weight. Neck holdng partial, eye contact sahi h nd moving objects p focus b kar rha h tv b dekh rha h cooing voices b nikal rha h hand grasping b hy nd hand to mouth Movement b hai. can anyone tell if it’s normal. attaching the reports. Kindly answer my query. Thank you