Help Ftm

Im a FTM and i breastfeed and bottle feed (formula) my baby he is 3 weeks & 4 days old. He drinks 3oz of a bottle and is still cranky after like as if he wants my breast i hold him and he finds it . I don’t know what to do or what is wrong with him. I don’t want to overfeed him for his tummy to start hurting. What can i do because this is after every feeding. He is a big baby and very greedy. At birth he was 8lb14oz . I ate aA LOT while pregnant not sure if that is the cause for his big appetite or what. Im very concerned please give advice / feedback ..