It will increase with time. My LC told me that between 1am and 5 am is when your milk supply is highest. If you have the patience to wake up then. I get about 2-3 oz after a feed between that time. Around 6pm I'm lucky if I get 1/2 to an oz after a feed. I also started drinking Mothers Milk tea, taking fenugreek, drinking lots of water and oats. My LC has me pumping after every feed for 15 mins(although I usually last 7 minutes) This provides me with enough milk to store 1 bag and feed 1 oz after every feeding.
My LO is a slow/sleepy eater so I have to offer him an oz after each feeding. Which is why I pump after each feeding, plus trying to build a freezer stash. He was only getting 2.2 oz in about 50 minutes when he sleeps eats.