The heal is probably not the reason, but put a piece of tape on your face and find out.

What is probably causing it, is your alignment. Get 2 clubs and put one down in front of your ball with the grip pointing at your target. Then the other down on your toes pointing exactly parallel to the first one. You should see the second pointing a little left of your target as in a railroad track like alignment.

Now hit shots. If this fixes your problem, on the course you can't use clubs to align yourself. You need to pick out points about 2 feet ahead from behind the ball, that the first club would be pointing at the target and the second, a little left of it. Set your club face at the first point, then step in so the feet align to the second point.

If this is not you problem, and you are hitting the face in the center, aligned properly, then you are simply pushing your shots. Usually a slide in the hips towards the target just a little will cause this. Try my walking drill and impact drill to help that out. But basically, keep your hips rotating and not throwing them out toward the target for extra power, all they need to do is rotate through the shot.