You've got what you need as far as call's go Josh. Now you need to learn how to move your tongue around on the reeds to find the clear spot on whatever call your using. Some cuts will produce a clear high end easier than others but it's really more about tongue position and pressure than it is about the particular cut. If your calls are rasping out on you too soon try "reducing" the pressure and moving you tongue around and you'll hit a clear high pitched note. Once you find it practice just making clear yelps.
I recommend you get Scott Ellis's new DVD Mouthcall Magic. He explains things in an understandable fashion. You'll also learn how to purr like a pro.