Though fcps has a good reputation, their reputation for special ed services is not favorable and services are being cut drastically. They will talk the talk and tell you all your daughter's needs will be met, but in reality she will be a number pushed through the system until she graduates.
You need an advocate to navigate the fcps system. I encourage you to invest a few hours of your time talking with a reputable advocate so you can then make an educated decision for your daughter's educational placement.
DCUrbanmoms special needs forums will have he answers your are seeking.
Good luck to your family. Welcome to the area. I wish I could offer you more optimism, but the reality is FCPS does not have a good reputation for taking care of special needs kids, especially with the ED label.
Go here:
http://www.dcurbanmom.com/jforum/forums/list.page