My baby boy is 3 weeks old now. He's strictly breastfed but I pump it for him and he drinks from bottles. But lately for the past 2 or 3 days, whenever he eats he doesn't burp afterwards. And I'll sit there for 10-15 patting his back trying to get him to burp. Every so often he'll spit up a few mins after instead of burping. I've googled and read a bunch of baby forums saying that breastfed babies don't need to burp as much as formula babies do but I was just wanting to know from other mom's perspectives or mom's that possibly went through the same thing with their newborns, is this normal? Like should I be worried?