Sam, I heard differing stories when I was going more often to neurologists. Some said that MS usually clustered lesions around the "ventricals", in a certain part of the brain. Others said that lesions could be anywhere in the brain. And then some people I knew in support groups then, who had diagnoses of MS, had lesions only in their spines. The ones with the spinal lesions said they thought they could "think more clearly" than the brain lesion people, and a social worker talking to the group said that could be true, but all MS people she had met had "loss of executive function". That sorta means you can't file things well, organize as well, and remember several things at once. I never had a spinal MRI because lesions showed in my brain. They were not periventricular so some neuros suspected them of not being real MS. They were more on the sides of my head in the temporal areas, first coming forth on the left, then on the right.

Maybe the neuro thought you recently had a brain MRI so the spinal one "covered the waterfront."

I went to a neuro my parents sent me to, at a teaching hospital, when I was your age, and he said I didn't have MS. (no MRI in those days).
Later when my eyes got worse, a lot worse, I got an MRI and VER, and they were positive. But that was decades later. Sometimes it just is a long thing. Please read Dr. Swank's book and other information and keep learning, as it may be something to live with for a while.