Is ir bad when my baby dosent burp after every feeding? She rarely burps?

Nope. Babies need to burp after feeds because they tend to swallow air with feeding. Some babies do not swallow a lot of air and do not burp. You can put the baby on her tummy for 10-15 minutes at a 45 degree incline after feeds if you are concerned and see if that helps her . If she is not fussy or gassy, there really is not a problem.
Not usually. Some babies are quiet feeders and don't swallow much air, so there isn't much to burp. The type of bottle may also make a difference. Breast feeding seems to cause less burping in general.