Hi there GolferDot, just going on the fact that your divots are going left, it is more that likely that you are indeed coming over the top!
In other words, the club is coming down higher/above the intended swing plane, thus you have a outside to inside swing path, (across the intended target line) through impact with a square clubface on that path! This would also explain why you are not losing any distance...it does sound however that this move is very small in your case and that could be why you are not aware of it!
I will try my best to explain in my words how you could try to work on this...
an over the top is usually caused by hitting with you right hand, the things that you could focus on is,
1. in your set-up try to relax your right arm,
this is to make it less active throughout the swing,
2. the move from the top of your backswing what you should try and feel is, your left hip moving laterally to the target (instead of rotating away from it) and at the same time, your left hand pulling down to start the downswing...
This would start the swing down on the same plane and would stop that over the top move...
I hope that this helps you a bit!
Fugly.