Low weight

I need help. My daughter was born at 7 lb 13 oz (left the hospital at 7lb11oz after a 2 day stay in the nicu). She is now 9 lb 8 oz at 5 weeks. Her dr said she went from 60%tile to 40%tile. And they want her to gain an ounce a day. They wanted me to try to breast feed then when she was done try to feed breast milk from the bottle to see if she would take more (maybe I wasn't producing enough). She generally falls asleep five minutes into her feed and it's like pulling teeth keeping her awake to finishe feeding. I feed her a bottle to see how much she takes. I tried really hard to get her to take the full 4 oz (dr wants her to eat 30 oz a day) and at the end of 3.5 oz she threw the entire thing up. How much does your baby eat? Does anyone exclusively pump and feed? I really don't want to go to formula but the stress of her not gaining weight and not eating well is taking a toll on me mentally and my supply. Anyone else have a similar experience?