8oz is amazing for 2weeks pps im 4months and only get that much every 4 hours. Its totally normal you will never drain them fully ive been told and often during a power pump session i see that i get a second let down after 30 mins of pumping. Look after your nipples make sure your applying nipple cream after each session, you can use coconut oil for the flange so that there is no friction.
If you can, try setting aside a few days (not necessarily consecutively) where you pump 15 minutes every hour on the hour for at least 6 hours (aim for 12 though). It’ll basically trick your body into thinking your babies are massively cluster feeding
8oz is amazing. I couldn't even get 3oz til 6-8 months, and my hormonal issues were kicking my butt. Keep going, Mama, drink plenty of water and rest/reset ypurself
If you haven’t already, make sure you are using the correct flange size…there are charts you can find online to measure your nipple to ensure you have the correct size. This can greatly affect milk output.