First of all welcome to our little corner of the web!
Your questions and concerns brought back many memories for me. I remember all too well the confusion and fear of "what if".

M.S. has a very specific criteria that must be met before a definite diagnosis can be made. Personally for me, the doc's were looking for M.S. for over 10 years before I got a diagnosis. BUT: My symptoms would show up and then pretty much go away. However; I did have this prevailing sensation of off balance that stayed with me most days. I continued to have a clean M.R.I.
Then one day out of the blue my M.R.I. came back with lesions consistent with M.S.

My advice to you is to let the docs go through all there tests to rule out anything that mimics M.S. This can be a long process. When nothing shows up, then you are in the waiting game for things like a positive M.R.I.

There is no good time frame for diagnosis. Its different for everyone. I will say that the day will come that a diagnosis of any kind will feel like a relief. It gets that "monkey feeling" off your back and puts you in a forward motion for treatment options.

I sympathize for where you are in this process right now. Its frustrating and scarey.....but hang in there and don't be afraid. Big Hugs to you and keep in touch to let us know how things are going