Help!

Hi, I need some help.

I am 24 years old and have never had sex. I want to save sex for marriage. My boyfriend (and future husband lol) and I do other stuff though (oral and fingering). We realized that I need both vaginal and clitoral stimulus to get off. However, no matter how good it feels, I can’t cum. I get so close but I can never go over the “hump”. I can orgasm when I’m masturbating. It feels amazing and my body feels so good when he is doing stuff to me, but I have never been able to cum. Am I in my head too much? Any advise on how to be able to help my body relax and cum?