Not that I'm a wealth of knowledge, as I'm still learning myself... but I would say that not only do you need to get your background lights further from the BG, the main light needs to be directed downward more. Usually it works best if the mainlight is shining downward, and the light is somewhat "feathered" on your subject. Almost like you're trying to bounce the light off the floor back onto the model.
In your "test" pic it looks like your model is just a hair underexposed, but then I'm on my work computer and it's not exactly calibrated.
Also, make sure your model is far enough from the BG not to catch any spill off the BG lights or bounce off the BG. If her outline dissapears and she looks like she's fading into the cloth, she's either too close, or your BG lights are too strong. The exposure on the BG should be no more than 2 stops higher than on the model. (If the light at the model meters f8, the light at the BG should be f11-f16)
Most importantly, have fun!
larry
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