From the sounds of it, your doc may be looking for symptoms that pop up and then are gone. Like for me...numbness in 1992 and again in 2002. All the other symptoms I had were kind of vague and could be attributed to other things....
Then there is the MRI.....need those multiple spots suggestive of Mylein disease for that positive diagnosis.
So; they like 2 or more flares separated by time....and the spots on the MRI.
I would ask your doc why: if you seem to have MS symptoms and spots on the MRI....why is he not convinced? Do the lesions look like they could be from something else? These two things alone got me my diagnosis. I never had a spinal tap and blood work was great except for one that suggested inflammation somewhere in the body. (disease was very active at that time)
You need to keep moving forward with this even if this means seeing another doc. ASK: WHAT ARE THE LESIONS YOU HAVE ALL ABOUT? DO THEY CORROSPOND WITH YOUR SYMPTOMS?
Hopefully you can get some answers.