you are working way to hard to turn. Let the snowboard do the work for you. like others in this thread have said. bottom up, first ankles, then knees, then hips ect. you can do this by opening and closing your ankle joint. If you are on your heel side edge looking down the mountain. First, push your front toe down. this will make your board start to go down hill. Once your board is at about a 45 or less to the fall line, push down on your back toe. This will finish your turn. Congrats, you just did a skidded toe side turn, now do the same to go heel side. First, lift up on your toe, the board will start to go down hill. once you hit your 45 or less, lift up on your back toe to complete the turn.
Rinse and repeat.