did they do all the basic tests for you and your fiance? how long have you been trying? for a healthy couple usually it takes around 6 months upto a year to conceive..so it should happen soon for you : )
good luck!
seek out the help of a Fertility Specialist or a Reproductive endocrinologist, They are the true experts and unless a plethora of tests have been run no one can admittedly say you are fertile with no prolblems, your issue may fall under the catagory of unexplained infertility. hope this helps
How much testing did they do? What tests did they do? Is your AF regular?