I read a little further back about driving your back knee into the direction of the turn.
This, combined with the high angle in your back foot could get you pushing your knee towards the tip of your board, which won't edge at all (which it appears you're doing).
Setup: While I agree with that Philfella about not tweaking the setup too much, I think you need to do the following... Try backing your rear foot angle off until you have your shell ends over the edges, when viewed from above. You may even want a touch of overhang (a couple of mm's).
The Move: Combine the level shoulders-thing and keeping a hand for each side (solid advice) with a knee move TO THE INSIDE of your turn, 90 degrees to your toeside edge. You'll feel pressure on the cuff of your boot to the SIDE of the tongue, not into the tongue. Your hip will not go in as much as the edge angle will be established to a large degree with your leg.
Look at pictures where riders seem to have their knees actively away from each other. This is caused by the drive to the inside with the rear knee, kind of like a moto road racer. (see the one guys avatar on the playground pony)
One last note on the toeside: Just because you're concentrating on sending the rear knee inside, doesn't mean you should feel all of your weight on the back foot. Try to weight both feet as much as is comfortable.
The heel turn is nice. With a stronger core you could run a bit more internal rotation, or "pelvic tilt". Allowing yourself to get "stacked" a bit more, from head to feet.
The Move: Feel like your lower abs are firing and your lower glutes are trying to curl up under your hip bones. This is a difficult position to stay in if you don't have strong abs. The benefit here is that if you hit uneven snow, you're aligned vertically and balanced. If you hit a bump overly folded at the waist, you'll huck-buckle.
I will take solid stance and pressure control over edge angle any day.
I'd worry about that last stuff later, as your heel turn is quite on right now.
Thank you for allowing me an outlet for this stuff. Hardly any recreational riders want high-end instruction around here.
Latre.