I too love frozen coffee drinks and have yet to find a recipe that is exactly what I want. However I do have some suggestions of things to try. Try is the operative word. Make small amounts and experiment with combinations until you find something acceptable.

Try Whey Low instead of artificial sweeteners. It has net carbs of 1 per teaspoon versus 4 for sugar and it tastes like sugar-really. I generally use a combination of Whey Low with Splenda and/or flavorings made with Splenda.

Try adding Thicken Thin Not Sugar to improve the mouth feel of the drink.

Get a blender that can really crush ice so you get a nice texture.

Try tofu, cream diluted with water, 1/2 & 1/2 or coconut milk for the "diary" in the drink. Look at labels as different brands have really different carb counts.

Try various flavorings to see which you like the best (chocolate, vanilla, caramel, others).

Start with really good coffee (best if decaf)-strong to compensate for the ice.

Good luck and keep trying. Eventually we will find a combination that is great.

I have tried the Atkins shake mix and to me it has an uncooked starch taste that is not pleasant.