I finally uped to nice shorts this year, and based off Pearl Izumi's sizing charts, I picked up small. I put them on and they were just slightly too small. I wore them anyways since they weren't too bad. They did reduce alot of discomfort for my solider, but with longer rides, I would get stinging/tenderness on the bottom of my butt like this...
(that little line on the right girl's butt)
Looking in the mirror after a long ride, the impressions left by the seams in my skin show that the sores are right on the edge of where the chamois meets that line
I rode with them for a while on shorter until they developed a slight tear around the seam of the chamois.
Since I figured the sores were because they were too small, I bought the mediums. Turns out they are too big, however, if I tie the draw string they are still rideable. Well it turns out that now I am getting the exact same sores on both sides (before it was only on my left side)