Thanks for the response! I kind of think you're right in saying she's silver bay, because I google searched sabino chestnuts and they had similar markings but they all looked much redder than she does. A lot of the bays looked darker than her, but I think they look closer to her color than the chestnuts. Your point about the body clipped color makes sense too.
How can you get a genetic test done? Is it expensive?
Genetic tests are done by yanking a bunch of hairs (about 30 if I remember correctly, making sure you get the "tags"/roots) and sending them to a facility that does the tests (PetDNA in AZ is probably one of the best, if not THE best to send a sample to). Most tests are fairly inexpensive, but not all genes have a test available.