how long does your baby nurse?

I'm asking because the longest my baby will nurse is 9 minutes and shortest 2 minutes and average around 4-5 minutes I'm worried he's not eating enough but he gets like 6 wet and 3 dirty diapers a day and I only give him a bottle after his bath just because I can see how much he's getting and he sleeps longer. Just curios I'm the only one my baby is 2 months old if that matters any