Pumping amount


My baby is 2.5 weeks old & we've had some struggles. She wasn't latching great so a shield was needed. Now she hasn't gained weight, so doctor wants her to nurse 5 mins each breast and top it off with a bottle of either formula or pumped milk, followed by me pumping to keep supply. We have done this since Thursday, and she definitely is more settled with bottle, but my concern is when I pump, I never get more than an ounce between the two. I'm trying to really increase water, cookies & tried the tea, but it's not changing much. When she is nursing, she is lazy and not effective which is also risking my supply hence pumping. I go back to work in sept and am so worried that I'll never get enough going to pump & store. Is this an ok amount at this stage, or am I falling behind?