Hi Franx,
Sorry you've had to come here but I can tell you first hand that this is a wonderful, informative and supportive community. Everyone here really helped me get my then 10 year old son from AA diagnosis, through unsuccessful ATG and then through a very successful unrelated BMT. He's 15 and a half now and the picture of complete health.
It's very good that you are taking your daughter to Seattle Children's to seek expert opinion and you are doing everything right in terms of finding and using the resources available to you to be your daughter's best advocate. Most specialists in the field of bone marrow diseases are very good and very thorough but never forget that it is not they who will lose sleep over your daughter's illness, only you and bottom line - squeeky wheel does get the grease. Don't let yourself be intimidated by anyone; you have every right to ask any and all questions until you are comfortable with the answers. You have every right to protect your daughter from infections by speaking up if you witness any member of any medical team not following best practice, like washing hands and wearing masks if appropriate.
A diagnosis and treatment plan is needed ASAP as you want to minimize the number of red cell and platelet transfusions your daughter receives and any time her neutrophil count is below 500, she is at risk of becoming overwhelmed with a fungal, viral or bacterial infection. My biggest concern when we were at that point was keeping my son away from every potential source of fungus/mold such as damp, dark places like barns, rooms or buildings that had old dank window air conditioners (big source of aspergillus) etc. Evan was home schooled during this time.
I believe it is easier for a child to cope with all this than it is for a teenager. They are just starting to have some autonomy and freedom and make choices for themselves. The best approach might be to emphasize 'short term pain for long term gain'. Following the medical team's instructions, being cooperative and taking her situation seriously will only help to ensure she returns to a normal healthy life in the hopefully not too distant future.
She could make her own account here on Marrowforums and seek to chat with other teens who've been there, like my son.
As far as what's going on with her marrow, the description 'dysplastic cells' makes me lean more towards MDS. With AA, there is simply a lack of cells but usually the cells that are there are normal, not dysplastic.
Seattle will be of tremendous help I am sure. Keep us updated and best wishes for a speedy diagnosis and treatment plan.
Evan's journey is described
HERE on Marrowforums, including a chapter written by him to other kids going through a similar journey plus his CaringBridge site is linked below which describes in detail his entire journey.
P.S. Is your daughter on any routine medications such as anti-epileptics or other meds that could have, over time, damaged her marrow?