I don't mean to be cruel, but the last one looks as if her water just broke.
First rule of thumb is to have your model 6' to 8' fron the background. this will diminish / eliminate the shadow on the wall because of the inverse law and focuses attention on the subject.
Secondly, if it bends..... bend it. As in #2. The straight arm syndrone plagues many a frustrated photographer. It is akin to the deer in the headlights look.
Be mindful of how you crop limbs and extremities. There is a way that can be more appealing. In a nutshell, mid-way between the joints.
These are NOT terrible, but with more time behind the viewfinder and due diligence in researching those particulars that are not coming across as dynamic at the moment, can and will be improved upon down the road.
Thanks for sharing.