How much should a 2 month old weight? My son is turning 2 months on the 28th and he already fits in his 3 months clothes. All my family members are telling me my son is to big for his age :(. I feed him formula about 3-4 oz. I feel like a bad mom I'm a ftm and everything is new to me. His 2 month check up is coming up too and I'm scared the doctor will tell me that my baby is not healthy because of his weight.