empty? How long do you pump for so that your emptying your breast completely. I want to keep pumping…

empty?

How long do you pump for so that your emptying your breast completely. I want to keep pumping so when i go to work my son on just straight breastmilk so im trying to make sure my breast are empty at every pump session i normally go for 20 minutes between both sides is that good i pump about 3-3.5oz a session with both sides and baby boys 2 weeks old i also drink mothers milk tea