Do you wear them with a belt currently? Or do they stay up?
Just size up. It won't kill you if they're a little looser, at least the stitching won't need to hold on for their dear lives whenever you sit.
I swear, there needs to be some kind of SW&D ceremony that welcomes in the fall. Maybe where one lays out all the knits and jackets and says a few words of prayer for the oncoming time of steez and swag.