I think there are a few of us with that problem on this site.
As far as jeans go, I've had good luck with Gap and Nautica brands, but only the loose fitting styles. I've found their waist and inseam measurements are more suited to short thick builds than any other brand I've tried.
Levi, and Calvin Klein are a waste of time as they seem to be styled for chicken legged types.
I can't really help you with the shirts, as I haven't noticed any consistency within a brand.