Why can't I cum?

So I’ve tried and tried and tried, but for some strange reason I just cannot get myself to cum! And this worries me. No matter how turned on I am nothings working, I’m not even sure if I know exactly where the g-spot is and if Im hitting it, why can’t I cum? I’ve even been fingered by my boyfriend and sometimes when he stops for a second I feel like I have to pee but when He starts to finger me again, that feeling just goes away. I’m confused, and I need help. Anybody please, got any tips?