I know you've heard it a million times before and you really don't want to hear it again, but some of the people who are telling you to try and not think about it so much might be right...
My brother was in a bad car accident when he was about 18. It was a little touch-and-go for a while with all his injuries. When he finally recovered, the doctors told him that the chances of him having a kid were about the same as the chances of him getting hit by lightning.
A few years later, he started dating a woman who had the same type of problem.. she wasn't supposed to be able to have children.
So, they figured they were a good match. They would understand each other and they wouldn't have to worry about getting pregnant, even if they wanted to.
Well, they never once thought about it because it was supposed to be impossible and one day it just happened! They called my mom so excited that they could barely talk to say they were pregnant! Now I have a beautiful 2 1/2 year old miracle nephew and none of us could be happier!
So, maybe if you did try to think about it less and to think more about alternatives (ie: adopting, accepting <- even though that's almost impossible in itself) getting your mind off it could be the trick. You never know. It's worth a shot. Like Jo said, the mind can work wonders.
I hope someday you have the family you always wanted. :cuddle: