Reflux?

My son hates being held sideways. He will literally scream anytime I try to hold him sideways. I can eventually calm him but then trying to feed him sideways makes him start screaming again. To feed him I literally have to stand, hold him as upright as I can AND bounce/rock him. Which is impossible for me because he weighs 20 pounds. And he will still scream bloody murder sometimes. If he’s super hungry he doesn’t seem to fuss much about how I feed him. So am I maybe offering meals too much? I usually offer every 1.5-2 hours. He does spit up all the time. I never have a clean shirt lol. I was going to mention this to the dr at our next check up, but wanted others opinions