Go out to a parking lot and keep trying. I learned to drive in six weeks flat (stick shift and all). I had to teach myself to parallel park (in the rain, at night, on a curve, on a hill, into a tiny space), but I still got my license. Keep practicing; get to know your car really well and don't read too much into the guy who gives you the test (I think they paid mine to be extra sullen and to mumble his requests).