I do not believe that story about her potential for pregnancy being okay for five years, and the, suddenly, it vanishes.

If you and she are in a committed relationship to the point where you are living together, then she's got no business having a male friend that she is this tight with. (He sounds like a boyfriend to me.)

You don't need counseling to talk you into becoming a dad. I think you made a mistake moving in with this gal. You two obviously (to me) have a lot to learn about each other. Being away at college was a healthy thing for you, and I hope you will be going back. It sounds like this girl just wants a guy who is always available to her. She'll take you, if you are around . . . or, if you're not, she'll take whoever she can find.

Don't go making any babies with her based on this "window of opportunity" story. Go with her to her doctor to have the doctor explain this rare condition to you. I think you're going to find this is a story she has made up.