There was absolutely no way this item would fit a wrist of 156mm as outlined on the website "42mm/44mm, Medium fits 156-178mm wrists". My wrist measures 162mm so by going off your measurements and size guide I would be a medium. However, the strap that arrived was 155mm and when you then factor in the 42mm of the apple watch face your wrist would need to be 197mm at a minimum to fit a medium size band. The error in the website is that it does not factor in the watch when stating the wrist fit. It should say band length. I emailed iStrap and still haven’t heard back. I pod for my own return and still no response. Utterly terrible.