Pumping after breastfeeding

Okay I know it’s normal to have a slacker boob but I didn’t think mine was this bad?? I haven’t pumped since my babe was about a week old...he’s now 11 weeks old. He only breastfeeds for about 5-10 mins every 2-3 hours and he wasn’t really emptying me today so I decided to pull out the pump. Well I fed him on the right side and when I pumped after I got 1 oz from my left and 3 oz from my right. How is that possible!! It also had been 3 hours since he ate off the left boob.