First, you need to focus on the eyes, so AI Servo & choose your focus point to put one there. 20D: If I switch my camera to Custom Function 13-1 to put point selection on the Multicontroller (Joystick), life with AI Servo becomes a lot easier. It only takes a fraction of a second to set the point I need.
Second, kids can generally handle dramatic light better than (some) older people, but for this sort of portrait, I'd prefer a softer light. So try putting a white card on the opposite side from the light to bounce some light into the shadows of her face. Closer is usually better, as long as it's out of the frame.
Not to complicate this too much, but another card over her head would help to separate her hair from the darker background, so if you don't have stands to hold the cards, you'll need at least one person to hold the cards for you.
#3: Too much room over her head. Crop to fit the shot, not to some arbitrary paper size, & then use a mat to cover the "excess" space in the frame.
https://photography-on-the.net …php?p=970537&postcount=17
A mat & frame also help isolate the image from the usual white walls that they're hung on, & can make a big difference in how it looks. Take a look at POST #30 near the bottom: The gray bar at the center is the same density all the way across.
A few Car Lighting Tips
The book background sort of works, but you don't need the white pages so close to her face. Actually, you don't need the white pages at all. Just darker bindings would be better, & having some horizontal ones mixed in with the others doesn't work for me.
This doesn't work, either: What was it about the shelf running through her face that appealed to you? 