I have a view on this but its probably against what you are feeling

I believe firmly that most amateur golfers cannot start the downswing their lower bodies, all this does is have people lose balance, or spine angle

What you may be doing by lifting your left heel off the ground is getting the right amount of movement off the ball (Jim Mcelans Y factor), thus really strengthening your backswing movement. My guess is this is where all your new found power is coming from

Stick with it though, whatever works !