FTM breastfeeding dilemma

So my little one will be 11 weeks Monday. We had to go in for a weight check this last Thursday since he was so tiny at birth (2 weeks early 6 lbs 3 oz) at 2 1/2 months he was only up to 9.5. Doctor said to start supplementing with bottles to know he was getting enough at least twice a day, I’ve been pumping (with only getting 2-4oz), staying hydrated, and eating well. It seems I’m just not producing. I’ve burned through the breast milk stash I had in just a few days. I feel so bad because know with giving bottles he’s mad when I breast feed and doesn’t act like he’s getting enough at all. Any advice? I feel like such a failure for not being able to do this for him. I’ve cried all day and I feel like my husband thinks I’ve failed too.