Might have something to do with the mechanics of your shoulder. Particularly if your hand is in the air, counterclockwise feels more natural than clockwise. Or at least, for your right arm.

What happens if you repeat the experiment with your left hand?

Same here, and I always write the “a, o” clockwise. I was surprised to see my circle drawing skill is better anti clockwise :-)

i think clockwise starting from the on your right hand naturally wants to drift rightward. Counterclockwise cancels the drift?

Have you tried switching hands and starting from the bottom?