Exclusively pumping

My baby is 2.5 weeks old. Im exclusively pumping because he wouldn't latch. I pump around every 3 hours, even over night. I usually only pump for 20mins per session and lately have been getting 2oz per breast. Should I be pumping until my breasts are empty? Or is the 20min session enough? Occasionally if I notice I havent pumped enough milk in the 20mins ill pump 5-10mins longer, but I don't usually have to do that. My boobs are constantly leaking, even right after pumping so Idk if pumping longer would be beneficial or if it could start an over supply...? 😩🥴