Well, Marie, I admire your determination. Serving is all about technique, and the toss. So practice practice practice. Take it step by step. Start with relearning the toss. Change your stance from your right handed stance to the exact opposite to start your left handed drills (correct position would be with your right foot forward). Then just toss the ball with your right hand and let it drop so that it drops beside and slightly in front of your forward foot. As you lift the ball and let drop, the whole time you should be holding it and letting it drop in line with your left shoulder. You need to do this until you hit the same spot on the floor every time. Even if it takes a thousand times. Now separately, when you take a break from your tosses, practice your hitting motion. This will feel real awkward at first, so here is a little trick. Practice your hit motion with your right hand first. Go thru the motion a couple of times, then do it with both arms together. Make the left arm mirror the motion of the right arm. Once you start to see how comfortable it is to do it this way then use just the left arm until it is comfortable with the new motion. After you have the toss consistent and the arm motion comfortable, start hitting the ball. Don't try to kill it, and don't even worry about getting it over the net to begin with. Just go thru the motions to get comfortable with them. Keep it up and the power will come with diligent practice and comfort.