A little worried about my daughter?

my daughter is 10 days old & she sleeps right through feedings & when i try & wake her up , she'll eat 2 ounces & fall asleep again no matter what i do. should i be concerned? im trying to wake her up every 2-3 hours to feed her but, again, she doesnt want to hear it. i am feeding, but alternating nursing & pumping. when she is wide awake, she takes both bottle & perfectly, but shes only wide awake after about 4 or sometimes 5 hours of not feeding. i feel horrible when i let her go that long without feeding but she doesnt want it!! help please?? she was 9lbs 11oz when she was born, & now weighs 9lbs 10oz, (had her weighed today). thanks