Burping a baby

I’ve got a stubborn 12 day old baby girl who loves to eat, loves to fart, but refuses to burp.

I’ve tried the over the shoulder and her sitting and one hand supporting the head and one tapping the back and she’s still a stubborn burper. Were using those dr brown bottles that are anti colic insert but I feel like we should still be getting a good burp from her every time.

What’s the trick, what’s the secret to good baby burps?