Not building a stash!

My baby is 6 weeks old. We had a rocky start with breastfeeding as she didn't latch properly, but I finally found a very good lactation consultant and since one week I have been able to almost ebf. In preparation of coming back to work, of the 8 feedings 6 are directly from breast, 1 is pumped bm and one is formula. I pump twice a day, when I give her the bottle, and I'm just able to produce 4 oz, enough for one feeding. I'm not making any stash! What can I do to increase my production?