It is the same with me. Dildos donīt do anything for me. If I want to come on my own, I like to say it takes 98 % head movie (my own imagination) and 2 % handiwork. *lol*
I would not worry so much. I think the "solution" is taking the pressure out of it (if you think you absolutely HAVE to come right now, it will NEVER happen), and trying to find the right guy - that is, a guy you are comfortable with. If you are at all like me, one-night-stands will do nothing for you.
While I was much younger, I got regularly accused of being "frigid" because, well, it all bored me. I used to think something was seriously wrong with me. I also faked orgasms often to spare the guy who worked his arse off the frustration (and me the accusation of being frigid) because I did not come during intercourse.
It turned out what I need is something else. I do not need lots of pain or beatings, but I absolutely need a strong element of dominance AND trust. I belong to the girls who get off on giving a blow-job without touching myself. *lol*
If that element is not present, it simply does nothing for me.
The romantic candle-light dinner, slow music, and long foreplay sort of thing is the most reliable way to turn me off completely.
Only with my hubby who is also my dom I experienced that itīs possible to come during pretty much any action. It was a long process, though. And I should add all sorts of things only started to happen because he never pressurized me, and never felt "hurt" or "insulted" when I did not come... I could speak about my issues with him, and he told me to stop worrying and just start to enjoy myself... and from the moment on I relaxed myself and knew nothing bad would happen if I would not come, I of course DID come. *lol*
As someone else said: If you can come on your own, there is nothing wrong with your physical functions.
And, again, I doubt you will find what you seek with a one-night-stand.