Fussy baby when drinking

han

My baby is 2 months old now... he starts to get more fussy when drinking. His usual drinking amount was 120ml (breastmilk/formular). Sometimes he was able to drink that amount when we carry him around while he drink sometimes he is unable to and will start to arch his back or push his bottle away, whine to reject it. Not sure what tobdo as we tried many methods to get him to drink. I don't want to pressure him too...