17 year old to not able to cum ?

Title says it all. I'm 17, I've tried 'beating off' for a good long while plenty of times. I've had a few wet dreams, but I can never bring myself to an orgasm when I'm conscious.

I think I might have come close a few times, but my 'head' gets so sensitive that I can't even manage to stand up, and stroking it more is almost like torture. Is that the point where you're supposed to keep going to make yourself cum?

I've never let a relationship get as far as a hand/blowjob/sex because of this ... Didn't want to end up embarrassing myself, ya know? So I don't know if getting my girlfriend to do this would make the magic happen.