What can I do to help my little guy stop spitting up after he eats? We use slow flow nipples when he…

What can I do to help my little guy stop spitting up after he eats? We use slow flow nipples when he gets bottled breast milk, i interrupt his feedings to burp him, ive tried sitting him up while feeding too. Whether hes on the breast or getting breast milk from the bottle he still spits up quite a bit after a feeding. Hes just a week old.