Is it enough?

So I had my son in July and I exclusively breastfeed. I pump on occasion mainly in the mornings if he hasn’t woke up the night before to eat, then I get anywhere from 3 oz total to over 6. Though when I pump during the day or in the mornings when he’s woke up the night before to eat I have trouble getting barely 2 oz total. Is that normal? How do I change that? Mind you he eats fine during the day strictly from the boob but occasionally wants a bottle which worries me sometimes.