It appears as you may have a few lesions. The non-specific means that they cannot tell what has caused those lesions. Lesions can be caused by many things. They can be caused by migraines, infection, lyme disease, MS and more. Unfortunately you will have to wait until that neuro appointment. The neuro will be able to check certain reflexes and responses that may indicate a cause to those lesions. I am assuming you have migraines with the mention of severe headaches. If that is the case, then you could indeed have a normal MRI; normal for someone with migraines. Again, migraines can cause lesions. Obviously I am not a doctor and I can't diagnose you.
I am sorry you are so worried about this. It is scary to have this hanging over your head. Good luck.