Advice would be awesome

Stephanie
So I could use a little advice from you experienced people who have TONS of breast milk frozen on top of breastfeeding. 
My little guy is 5 weeks old. I'm ALWAYS stressing about if he's getting enough. Even though he's content for several hours between feedings, he's got enough dirty and wet diapers, I just am always anxious he's not getting enough. And he takes forever to nurse, but has gotten better. 
I want to be able to just nurse him on one side and pump the other but am worried (again) that he won't be getting enough on just the one side. Since right now he eats both sides for about 15 minutes (at least) on each side, but he gets pretty sleepy once on the breast. 
Any advice from you mommas that do this? Will he eat sooner in between? I hate feeding so close together all the time. And I don't know how some of you moms with younger babies even can pump out so much. Even when he hasn't fed I can only get roughly 3 oz out total.