breastfeeding with no weight gain

Im not a ftm, but it my first time breastfeeding. my lo is 11 days old. Her birth weight was 7.0lbs, at discharge she was 6.11, 2 days later at her first appt with the pediatrician she weighed 6.6, and today she weighs 6.4.. Im concerned, the peditrician doesnt seem to be too too concerned because she is peeing and pooping normally, and having the correct amount of wet and dirty diapers. He said she will catch up, but i get discouraged because i feel im doing something wrong. In the hospital i was feeding her as she needed, every 5 hours. she wouldn't wake up to feed before that, and i tried to wake her up and she wouldn't wake up. By day 3 she was feeding every 4 hours, and day 5 im feeding her every 3-3.5 hours. what can i do differently? and have any of you moms experienced this.?