Tummy aches or just playing with us? How much and how often should a 5 week old baby be eating?

I can't really argue with your doc's advice since I'm not a doctor but as a second time mom I am much more relaxed this time around in knowing that my child will let me know when he's hungry. He eats about 4oz about every 3-4 hours, most times it's closer to the 4 hour mark now that he's 9 weeks old. However, since he was about 3 weeks old he sleeps roughly 6-8 hours through the night before waking to feed. I usually feed him his last bottle at 9pm and he wakes up anywhere from 4am-6am before wanting to feed again. What I've learned is that so long as they are gaining weight, they'll let you know when they're hungry. Don't overfeed! Also note that when babies belly's hurt they will tend to act hungry and take a bottle when in fact it just makes the situation worse. Only you can know as a parent what your babies clues are though.