Newborn not gaining enough weight

M

My 12 day old isn’t gaining enough weight. He was born at 6lbs9oz, dropped to 6lbs2oz at first doc appointment which is normal. That was 7 days ago and he only gained 4 oz since. They want to see 1oz gain daily. I’m feeding him every 2.5 hours and supplementing 1 oz after each BF. I met with lactation consultant and that’s the plan they provided. Now they advise I supplement a whole 1.5-2oz after each BF session. Anyone have a similar situation or can comment? I’m tired and exhausted. I am feeling like giving up on breastfeeding. I also feel like a failure. I pump after each feeding. I only get about 0.5oz. I’m feeling very discouraged and down.