Looks like lots of excess fabric at the waist and hips, you were just sweeping all those to the back, which looks very apparent. You shirt will come untucked too easily. Maybe a side view would help, but I think you have a flat seat, leading to bunching of fabric behind your pants. Still looks low to me though, could be a photo illusion!
Looks like a shirt that should be tucked in, seeing that it tapers at the waist and then flares out at the hips. I'd prefer a straight cut if its to be tucked out. Yes, sleeves are too long. Then another problem, looks too short to be comfortably tucked in? Or you are wearing your pants low.