How long during breast feeding sessions?

This may sound dumb, but bear with me. I am a first time mom. I’ve been exclusively pumping almost the whole time I’ve had baby. I was breast-feeding the first week or two but quickly stopped because he had a bad latch and was not getting enough so I switched to bottles to be sure that he was getting what he needed. I will occasionally breast-feed during times that he’s cluster feeding and it’s just too much to pump. I think I wanna start breast-feeding at night again just to make it easier but now that baby is almost 8 weeks old and I haven’t breast-fed a lot I’m unsure of the specifics. How long do I leave him on each breast to ensure that he’s getting what he needs? Do I wait for him to pull off? But if he pulls off does that mean that I don’t put them on the other side? I want to be sure that he’s full, especially at night to go back to sleep.  he eats usually every 2 1/2 to 3 hours and almost always does 3 ounces each time so I want to be sure that he’s getting that if I’m breast-feeding. thanks!