I would be encouraging her to eat as much as possible personally. Trying to keep her awake and nursing longer. When she starts to drift off switch sides and try to get her to latch again. Do breast compressions to get her a jet of milk and hopefully wake her up and get her drinking again. I'd also be offering her the breast pretty much any time she even thought about getting restless or showing any kind of hunger cues. (sucking motions, hand in mouth, rooting etc.)
Are you still pumping and supplementing with a bottle?
Kristy, wife to Josh proud mama to Katie: since 3/08 and Emma since 8/12.
My son nursed for hours to get milk milk established. Then he nursed for like 5 minutes at a time. So yes, it happened to me. But he was eating quite frequently, about every hour or so.
Put your baby on the breast whenever she'll eat and you should be good.