The very pale green is very nice- soothing and easy to accent with pink. You won't really be able to tell how it will look with so much of the darker color still on the wall. You might even go a bit lighter on the green, and take away some of the yellow in it that is clashing with the window blind.

When you can't match something it is usually better to pick something a bit different, in this case it is the lighter green which I think will work well with your window treatment.

What does the 6yr old want? I would pick out the bedding and everything else before deciding on paint.

I would paint the walls pink or blue unless she really likes/wants green.