It might be worth your while ringing Great Ormond Street, and seeing if you can talk to a haematologist (I'm not sure how easy that will be to do).. Explain the situation and that you are considering bringing her back to the UK and see what they advise.
DXWombat, I'm not sure what you are thinking of regarding the normal loss of Fetal haemoglobin. Your statement is indeed correct, but it shouldn't cause an Hb much below 10.