my baby won't burp

Jackie • 24 y/o Jake G 💍 mama to LNG 4/21/17 👶💙. SAHM . Idgaf about your opinion. It doesn't phase me🙌I say whats on my mind. Gtfo my page if your a hater. I don't need that type of drama. Stay blessed . 🙏🏻
So we my son is 5 weeks old we feed him between 2-4oz every 3 hours. After feeding him we try burping him and he doesn't burp!!! 
Idk if it could be the formula as we did switch him to the similac pro sensitive formula.idk if the formula is causing him not to burp. But we tried everything!! He does any farts lot tho. Lol Any advice or recommendations please?