Advice needed!!!!!!!should i marry him

I have been trying to have a child for a couple years with my fiance...however i am NOT supposef to be able to have kids and he knows this but wants to try anyway...he is pressuring me to get married soon but i don't wanna trap him with someone who can't give him the one thing he really wants so should i go ahead and get married or should i try to get pregnant first so that if it isn't in the cards i can spare him a life without children!!!!!!! All comments welcome