Baby act like starving 3wks old what do i do?

My baby is 3 wks old and he eats 2 1/2 to 3 oz at a feeding. He wakes up every 2-3 hours and acts like he is starving like the food is not enough. He also sometimes spits up and makes me think the 3 oz is too much, but he acts hungry all the time I try to sometimes give him a pacifier, but he will spit it out sometimes and wants more milk. People keep telling me to put a tiny bit of rice cereal in his bottle, but I don't want to right now. Anyone have this issue what did u do?