Breastfeeding

My son is over 2 weeks old and only started to latch about a week ago. He’s eating every 2-3 hours, but usually only eats one breast from anywhere from 5-15 minutes then falls asleep. I’ve tried all the tricks in keeping him awake, but even if I do manage to wake him, he will not take the other breast. At his one week check up he had surpassed birth weight, but that was before he started latching and i was pumping and bottle feeding. How long do your babies nurse for? How can I be assured he’s eating enough?