I'm 5'2 and 120 lbs and have the same problem. I usually wear polar fleece pants that one of my daughters bought me in a short length, but they don't work real well when there is a lot of snow because the snow sticks to them from the snowshoes kicking it up. I found a cheap pair of ski pants at Gander Mt that worked pretty well last winter in a short length, but they are too insulated for hiking and I've been looking for something else.
I did notice that LLBean has a pretty big selection of winter hiking pants and they always have short lengths. I bought a pair of regular hiking pants (northface) online since I couldn't find petite length anyplace. They got a little chewed up with prickers in the Western part of the Catskills this summer, but they dry nice and quick. The online stuff is usually cheaper and you get reviews which is nice.
I think more men hike than women, so it's probably a money thing like everything.