I also have a narrow face so large sunglasses don't work for me. I've been searching for square plastic framed sunglasses forever but can't find what I want. Most of the smaller wayfarer types are rounded and if I do find square frames, the lenses are 57mm+. If you're looking for aviator style sunglasses, the American Optical pilot in size 52mm work for me.
52mm? i dont think ive ever tried on glasses that small... i shall check em out. I think 55-57mm work ok usually, it just depends on the overall shape.
Most glasses that i see out there at the moment seem to be 60-65mm which is just ginormous on my noggin.