Reflux baby burping

My son suffers from reflux and I burp him after every ounce of milk. Sometimes he burps straight away and other times it can take a few minutes to get the burps up. When it takes longer to burp he arches his back and cries so much and I can’t put him down straight after feeding him as it reflux back up his mouth and reflux dribbles out. He suffers with milk protein allergys so on similac formula. He doesn’t drink a full 4 ounce bottle most of the time only drinks 3 ounces. I try for up to an hour he won’t drink anymore. Should I burp him after every ounce or after every 2 ounces and what advice can you give me on how to manage his reflux he is 9 weeks old. I cry for my baby when he has it.