Spanner89:
Your girlfriend is good in front of the camera. Let me suggest you go back to the images you posted and look at images used in glamour mag's. Then ask yourself what's the difference? When you start answering your own question, you'll beging to get better.
Some sugg's:
Try to get some contrast between the backdrop and the subject. Unfortunately your girlfriends clothing blends right in to the background.
In addition, look at the color difference between images 1-3 and 4-6. Images 4-6 have a yellow cast to them. I'm not sure if you have a white balance issue or if you changed your lighting bewtween them or what?
I always try to put my subject about 6 ft in front of the backdrop. This allows you to place an additional light to splash up on the backdrop and position it to hightlight the backdrop between the shoulders. In addition, it helps to increase the contrast between the subject and the backdrop.
The 6 ft. distance bewtween the subject and the backdrop helps to put the backdrop out of focus. Remember the object is to answer the question - "What's the subject"? That means everything should be lighted and position to put all the emphasis on the subject.
Regarding backdrops. It sounds like you're using seemles paper for the backdrop. If so, then roll the paper up - don't fold it. This will help eliminate creases.
Try the sitting again and see if you can try to put more attention on the subject. Good luck!!
Feel free to post again or email me with questions.