Am I bad when it comes to sex?

My boyfriend barely EVER cums when we have sex. Like it's not even like he's trying to pull out kinda thing because I have the IUD and don't really worry about getting pregnant. But whenever I give him oral sex he cums no problem. Like is that normal for a guy? Or is my performance during sex terrible?! What could I do to improve it if it is! It really makes me feel insecure about myself sexually.