I use regular fleece tights for running with my bike shorts underneath. That way, I can use them for walking or snowshoeing. I am 5'1" and one pair fits almost perfectly in a small, although I usually wear an ex small. I have another pair of tights that I think are Pearl Izumi that definitely have too much fabric. I try to bunch it around the bottom of the legs. It's too bad, because these are a bit warmer. I also have a pair of Ibex tights I use for x country skiing, snow shoeing and winter hiking. They are more waterproof and made of wool. They fit perfectly in a small. I have worn them with bike shorts underneath for mountain biking in the fall and winter and on the few times I ride on the road int he dead of winter.
Athleta carries many types of tights (no chamois) in petite sizes. I would look there.