I was drawn to her legs, and where the photo was cut off. If you're going to put her legs in the photo, put ALL of her legs in the photo. When you only include part of them, it doesn't seem as natural, you know?
In all of these photos, I would have gone the opposite way and actually included her whole body. Number four, concerning her, is nice though. Cause it includes all of her shirt, and none of her shorts, it looks natural.
When you're looking at a photo, look at the subject as if he/she were parts. Like her shirt is a part, her arms, her shorts/pants, her legs, etc. If you're going to include one of these parts in the photo, either include all of it, or none/almost none of it. Some people may be able to clarify more, but when we see a photo we break it down into parts. And these parts need to either be in the photo or out.
Great stuff, though. IMO with more experience and more trial and error, you are going to be GREAT.