Yes, you can 5% experience no lesion on MRI at all.. this does not mean you have ms though.. all things need to be looked into..
Wishing you the best, MS is not the best or the worst case scenerio... have you had a spinal tap??? There is also a retinal eye scan that can be done, it is pretty good at checking for early stage optic neuritis... before MRI picks it up.. This is not the "gold standard" yet or used with neurologist.
It is done by eye dr's... just something to check into.