Pumping and Nursing

I have exclusively nursed my baby so far... he’s only 2.5 weeks old. I am starting to pump 2x a day. How much should I be getting during pumping sessions? I’ve been pumping after he nurses. Trying to figure out the best settings for my boobs. I’ve been getting very minimal milk... like .5-1 oz per boob. This is after he nurses on each side for 15-20 minutes.