Lisa - you and I have almost the same waist/hip measurements. I ride a Brooks B67 and wear M in Ibex biking capris and L in Terry biking skorts. (Those two things are my favorite biking clothes.)

Mind you, I haven't worn a "M" in ANYTHING on my butt in decades, so I think Ibex runs large in their biking stuff.

I have a pair of Hind shorts with leg bands that actually gap and flop around while the waist and hips are comfy. Maybe look at some Hinds if you need to scout out other shorts?