My 12 weeks baby seems to be hungry every hour or hour and a half.?

My son is 12 weeks old and make 3 months on the second. I feed. He was a preemie but he weighs 12 pounds now which is normal. He caught up fast. I am a young mother and a first time mother. My mom always tell me he is hungry everytime he cries. It's been almost 3 weeks I've been feeding him like every hour and I'm sure it's not a grow spourt. He sleeps a lot also. When he wakes up during the day i feed him and he goes back to sleep. I don't know if I'm feeding him and he isn't hungry and it's something else. My doctor said I've been over feeding him and I can make him wait 3 hours now since he is big and older. I've been doing that for a day now. I give him a pacifier when he cries. It makes me sad to make him wait. I don't know if he wants to be feed every hour because he is use to it or not. I've been searching and they said they will eat normal agin later but it's been 3 weeks. I don't know what to do. If i over feed him he can have a chance of diabetes which runs in the family. Should I feed on demand or make him wait 2 hours and not three. help? oh. making him wait 3 hours lets me sleep 4-5 hours at night which i never had.