Bizarre Sizing

I'm a thin 5'9" woman, and I spent weeks reading the reviews here and deliberating over which size to get (small or medium). I even contacted the company for sizing information, but didn't receive any specifics, just that the jacket is "men's sizing and cut large to allow for layering".I finally decided on a small, which arrived last week. Surprisingly, the arms were just the right length for me (although my arms are long, so normal sized people might find them too long), and there is tons of room around the torso for layering (a little too much room, in my opinion). But here's my main problem with it: the bottom hem of the jacket is VERY narrow. It barely fits over my hips and backside, and as I said, I'm pretty thin. There is an elastic cord through the hem (for tightening, not like I would ever need that), but of course it can't stretch any wider due to the lack of elasticity in the jacket itself. I feel like I'm going to rip it when I bend over. I realize that windbreakers need to be somewhat narrow at the bottom to protect from wind and water, but that's what the elastic cord is supposed to be for. So basically, if you've got long arms, a large torso, tiny hips, and no butt, this jacket is just right for you.Also, there is a zipper inside the back of jacket, and for the life of me I don't understand its purpose. It only goes partway across the back, so it's not like the lining can be removed. The sewing and workmanship is poor, too: the cloth around this zipper is gathered unevenly so that it bunches up, so heaven help you if you're wearing the jacket while sitting against a hard surface; the bunched-up cloth digs into your back mercilessly.I'm disappointed overall.