1 month old advice

My 1 month old will take about 4oz and then 2 hrs later he acts like hes hungry again? He only does this during the day. He takes his pacifier like it's food. Should I still offer him more? I'm just worried about overfeeding him. He also spits up alot. (I've already talked to his dr about him spitting up). At night, he wakes every 3hrs sometimes 4 for another 4oz.