Can I suggest while you are waiting to see if it is reflux that you take him for a walk in the pram about an hour to an hour and a half after he wakes up in the morning. The fresh air always calmed my kids as babies (even just stepping outside stopped them screaming some days) but also the motion of the pram may get him to sleep and then you can wheel the pram inside if that is possible so you can do what you like. Also try some white noise, you said you have a carrier so perhaps vacuum while he is in it to see if the noise helps him.
My DS1 was similar in that he drank all day because it soothed his reflux but it also made it worse. Does your DS have a dummy? It helped me to get a little longer between feeds and let him suck like he wanted.
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