Kaz -
I've painted a number of mummies in my day, and I occasionally deal with them in my line of work, so take that for what it's worth, as I get a little weird about them;)
You've done a great job, and you should be proud of it. My only suggestion is that you ink or dip your mummy with a dark brown or black. I see a lot of mummies that have a distinct look as if they've been partly covered in furniture polish - it's usually the result of the use of the resins that were poured over the mummy during the mummification process mixing with the perfumes, oils, etc. that were also used.
As a result, when I paint mummies, I usually do them almost exactly like you have here and then wash them heavily with brown or black. (Which color really depends upon the mood I'm in at the time!)
As an extra bit, I would also suggest painting the skin in a darker shade. Mummies, even Caucasian ones, that are preserved in the Egyptian way tend to have very dark skin, again because of the mummification process. That isn't totally necessary, as I think your mummy is fine as it is, and I often skip that step myself, just a random suggestion that I think looks good with certain models.
-Doc