You might just need to relax and do what comes natural. Your best bet for getting off is to be on top and use loss of lubrication on your clitoris. Just enjoy the intimacy and when your really getting into it mentally coach yourself (oh yeah this feels good).if he is doing something you like tell him. You have to talk and guide each other. Good luck girl!
The easiest (and maybe only) solution to this problem is for you to take steps to become more comfortable giving yourself pleasure and practice practice practice. If you can't do it yourself, it'll be a miracle partner who can do it for you. Just start slow and easy, try books, try some toys, and start playing around down there by yourself when you can relax. As you become more comfortable in this setting, start introducing your partner into the mix and eventually you'll know well enough how to get off that YOU can be the one teaching HIM how it works. Good luck!
I think your wanting to pee maybe the urge to squirt? but there's grey area surrounding female ejaculation and the existence of the g-spot and getting orgasms from the "g-spot"