Baby never seems full?

hey guys..I had my boy on the 22nd June 2019 weighing 8lb 13oz.Hes a month old now and is drinking between 5/6 oz.Ive had to put him on hungry baby as he is ever so greedy,but this doesn’t seem to make any difference..he still wants his bottle every 3 hours and is the same at night? Am I doing something wrong (I’m a first time mum btw)