Ok, I know from my aunt who has MS, and my eye doctor about this. Typically you either lose vision completely (usually in one eye first), lose your ability to see color, and have bad pain when moving your eyes. My eyes always hurt when I move them too far to the side, so don't go trying to see if your eyes will hurt. I'm talking bad pain when you move them a little.
My aunt said it's very painful, and you can't mistake it for nearsightedness. It's totally different. Both my eye doctor and my aunt told me those three symptoms I mentioned. I have worried about optic neuritis before, as well, but not for MS related reasons. You need to stop thinking you have MS! You're so young.