Be it Ehrlichia or Anaplasma, I would treat 8 week at the aggressive dose for ure if there is blood results as you describe. You can assume that your dog is in the chronic stage. I would run a cbc in a week to make sure they aren't continuing to drop. If this is the case, you might need prednisone, but you want to only use that in lifesaving situations, as it will interfere with the antibiotics.
Whateve liver support herbals that you have available would be helpful. I know someone in Costa Rica spoke of a popular brand, but I can't remember what it was.