Cupcakegirl,
I'm very surprised that the doctor hasn't given you more information by now. It might be a good idea to start making a list of questions for the next appointment with your daughter's hematologist.
There are many possible causes of fevers or a low white blood count. The information you've posted isn't enough to conclude that it's a bone marrow problem, or that it isn't.
Here are some questions that might help you learn more about what's going on:
What causes of your daughter's symptoms does the hematologist consider to be possibilities?
What sign is there that it could be MDS? What about aplastic anemia, which for children is more common (actually, I should say "less rare") than MDS?
What other tests have been performed and what tests besides another bone marrow biopsy should be considered?
Is her fatigue due to a low red blood cell count (anemia) or is her red blood cell (RBC) count normal?
You can find other possible questions
here.
Let's hope your daughter doesn't have a bone marrow failure disease, but instead something more easily treated.
I suggest that you get the free
information packet from the Aplastic Anemia and MDS International Foundation (AA&MDSIF) and ask them to include information about both aplastic anemia and MDS, unless the doctor has already ruled out aplastic anemia.