Cindy,
I agree with Renee's assesment. I don't always do a grisaille under painting, but when I do, I've been following Karin Well's method, which is similar to what Renee describes.
Yes, this is definitely a "valid portrait"! Your daughter is perfectly suited to this pose, and her expression is captivating.
For some examples of borrowing from Vermeer, check out Jonathan Janson's website:
http://newvermeers.20m.com/index.htm
If you're a Vermeer lover like me, you'll also want to look at Jonathan's Essential Vermeer site:
http://essentialvermeer.20m.com/
I'm looking forward to seeing how this turns out.
Cheers
John