Boyfriend can’t bring me to orgasm...

We’ve been dating for about 6 months now and things are great and I’ve been able to make him cum just fine via handjobs and blowjobs but when he’s tried fingering me I can’t finish! It feels great but I don’t really feel that build up that you get right before. We’ve had sex but I haven’t able to finish then either. He does really try which I appreciate and he does turn me on but after like 30 minutes of it we give up! He’s eaten me out before, or at least attempted to, but to no avail. I get myself off just fine, though it does take like 15-20 minutes. I don’t know what’s wrong with me! Am I the only one? How can I help him get me off?