At first I thought the white was too white. I think of the SW as being more sand/beige colors, but this quilt has a lot of the same colors and the white looks fine. When I did a Yahoo search for Navajo quilt images I saw a lot of patterns with white, reds, blacks and others with oranges, beiges and both types mixed with blues. I think it just comes down to whether you like it and whether it matches the room or painting or whatever it is you want to match.
Footnote: I always question my choices about half way through a quilt and typically don't like much about it. But then....I finish it and get it quilted and fall in love with it again. I think your choices are quite lovely and will look very SW when you are finished.