That is so weird. I bought the same pants. It seems like I have the same measurements as you too, (31" true waist, usually 33" denim and such). I even have really large thighs and calves and that was the only problem I ran into. These fit pretty damn slim but not unwearable (I think). Waist was okay. The rise is pretty big to be honest.
Yeah I mean they just aren't that comfortable because I have to sag them so much. I can't really pull them up higher because they won't fit my legs. An XL would be much better in my thighs and the waist.
I'm pissed because I bought a L in the sweatpants that is coming today, as I wanted something a bit more slouchy and stuff. Guess I'll just have to throw them in the dryer.