Breastmilk not keeping baby full?

I feel like a horrible mom. I started BF when baby was born. He’s 6 weeks and had to switch to pumping because he has a terrible latch and wasn’t getting enough. I was pumping plenty and then the doctor said to give him more because he wasn’t gaining enough. I haven’t been able to keep up so I mixed formula and breastmilk to get me the 3 oz he needed. I finally got a big enough stash that I got rid of formula and got him back on breastmilk! It lasted literally 2 days because I am not pumping more than 1.5-2oz per session when I used to be able to pump way more. Not sure what happened… I never stopped pumping btw- always did every 2-3 hours even when supplementing. So not only can I not provide him with enough breastmilk because the stash is gone in 2 days but he’s been screaming to eat at like 2 hours when he could go way longer. I know that formula is thicker and takes longer to digest and he probably got used to it but I feel like my breastmilk alone isn’t satisfying him anymore 😫 I feel like giving up and going straight to formula. The fact that I could only do this for 2-3 weeks before running into supply problems is hard. Suggestions? Or just switch to formula so I know he’s taken care of?