Before my son, then 9, was diagnosed with AA, he had drenching night sweats and bad dreams. This was even before he started bruising so I'm assuming his platelet count was still adequate. He would also complain of achy leg muscles. It is possible that your daughter is in the earlier stages of AA. While no one would wish this on their worst enemy, it really is a good thing that this has been discovered this early.
A second BMB in a few months would be very worthwhile to see where the cellularity is at.
We are in Ontario and when Evan was diagnosed, I reached out to Dr. Margolis at Milwaukee Children's Hospital via email and he called me without hesitation. He offered his opinions and answered my questions pro bono many times throughout our year-long journey. He is a Pediatric Hematologist/Oncologist specializing in aplastic anemia. I also recommend you be in touch with him.
Best wishes to your little girl.
Nicole, mom to Evan (20); diagnosed SAA November 2007, hATG mid-November 2007, no response after 6 months, unrelated 9/10 BMT June 2008, no GVH, health completely restored thanks to our beloved donor Bryan from Tennessee.