Pumping & building a supply

I've had a low milk supply. At 2 weeks old - 6-8oz was my max pumping a day w 8 pumps. (I had to stop BF due to latching trouble and tongue tie). My baby is now about 4 weeks and I'm hitting a max of 9-10 oz a day. I'm supplementing with formula and she does about 24 oz of formula & milk total a day