I have a 3 month old bOy and he weighs 12lb 9oz now he was born 2 weeks early at 5lb 7oz. He will go the entire day with only eating 8-10 oz then come 5 o'clock- midnight he will eat about 15-20. Is this normal? He also will only eat an oz at a time usually sometimes 1.5. For the first two months he was eating about 27oz and 3oz at each feeding. Help ! Stressing mama out