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Supplement with breastmilk instead since you have a good supply. The good thing about pumping is that if you empty a breast by pumping, you get the thin front milk that is so easily digestible, AND the hind milk that holds baby longer, and it's mixed together for you to feed her in the bottle. Put two ounces of milk in each bottle at a time so that you don't waste milk.
Some babies don't suck well because they need a bigger hole in the bottle nipple. You can get nipples that have bigger holes. We found that out with one of my babies who I thought was a "lazy" eater, and it helped a lot.
Keep baby awake by using a cool washcloth to wipe her face and don't have too many clothes on her to make her feel too comfortable. That will help keep her awake.
If for some reason you need to use formula, try Good Start - it's easier on their tummies. Or ask the ped for advice for sensitive tummies.
Good luck!