My son has never been a long eater even when he was a newborn. 2-7 minutes. Maybe just let him stay on one side each time. My son is 5 months and 20 lbs so I know he is getting enough milk. My daughters weren't even 20 lbs when they were 1 and they ate forever. I think you just have to pay attention to growth for your child and the rest the others mentioned. You would notice if he looks unhealthy.