Quote:
suddenly it was like she just tilted over a few degrees from vertical and switched direction

Yes, unlike the classic Necker cube she's in perspective: her toe traces out an ellipse, not a straight line. On the assumption you're looking at her from normal eye level, the lower part of that ellipse must be the front, so she's going clockwise. To see her going anti-clockwise, you need to imagine your eye-level being below her foot level.

Peter