You've just identified your own two faults. Swaying and trying to hit the ball too hard. Stop it! and you'll play just fine. If your playing off 15 now, then you are likely to be pretty consistent on the course. Don't worry about having a rough game now and again. We are never going to play in The Masters, or the British Open, but you are unlikely to start hurtling back up to the high handicaps either. Relax and enjoy the game and you'll play at your best.

Cheers.
Lee.