My daughter is 3 weeks old and can practically sleep through the night. Her pediatrician said I should wake her every 4 hours at night to feed, which I have been, but I feel like I should let her sleep. She eats plenty throughout the day, and she has plenty of wet and dirty diapers throughout the day too. I don't want to disturb her rest if she isn't hungry, and it's kind of nice for me to sleep too. At birth she was 5lb 12oz, she didn't lose any weight in the hospital, and at her 2 week checkup...