What size of pants would I be with 37 inch hips?

US size.

Measurements: 34c-31-37

I have been noticing stores have been reducing the sizes and i havent gained any weight. Im 5'7 and all there are is low rise jeans! I have gone to stores like wet seal, papaya, and forever 21 and im a large or medium. In other stores im only a medium and a small in shirts! So why is it in stores like those that im a large when im not overweight? Are their sizes reduced? This is confusing because I can barely fit into a medium in forever 21 and papaya because from my thighs its fine until it gets to my hips. Sometimes i fit into a small in those stores, no sizes are the smae and its frustrating! What the hell?

What is wrong with these stores, I work out almost everyday so why am i finding it harder to find some normal clothes that not to small. Because the medium is too short?

What size of jeans would i be in US size?