My 3 week old is breast fed. Usually wakes up every 2 hours for a feed. Today its been around every 3 hours and she is currently still asleep and its been just over 4 hours since she last fed. Just tried to wake her up to offer a feed but she was not interested and had just gone back to sleep. I know i probably sound mental but is this normal? I read so much info saying that babies MUST feed at least every 4 hrs and if they dont then wake them up then i read if they need it they will wake up for it. Im just so easily worried