Beautiful filly!!
I think she looks silver buckskin.
When my foals that are silver (bay, black, buckskin) where born, the silver in the mane and tail came as they shedded their baby hair. And the silver bays legs got darker (from blonde to grayish black) with age also, and could take as long as 4 years of age.
So my guess on her color is, she IS a silver, buckskin 1st, bay 2nd, and then black 3rd. It will be interesting to see what everyone else thinks.