You might also try sleeping next to her in a safe cosleeping set up (mattress on floor, no pillows or blankets, keep pets & other kids away) and keep your breast out and available right by her mouth as she sleeps. The closeness will help stimulate her rooting reflexes and stimulate your milk to continue building.
Not sure if you're already doing that or not.
My DD was a very sleepy newborn and barely woke enough to nurse the first week. She lost 15oz and had me freaked out. :-/ So we spent the next week topless and snuggling.