I know that the thoughts of a spinal tap are not what folks want to hear from their physician yet in the hands of an experienced practitioner it really is a simple procedure and relatively painless. It will also provide a more definitive diagnosis.
I hope you hang in there as there is hope on the horizon, I am not familiar with what alternatives are available in your area, however, there are now many options available for folks with this diagnosis.
I think it is extremely important for you to maintain a positive attitude, maintain a strict bedtime routine, utilize bright light therapy and vitamin D supplementation along with a regular exercise routine, these few things are as important to your recovery as any medication will be.
I certainly wish you all the best and please keep us informed