Hi Imp, and welcome 
Bipolar disorder is surprisingly common in MS and the rest of your symptoms are often found in MS so your history does rather sound like MS to (unqualified!) me, assuming that the various explanations offered by GPs have been wrong. Of course, it’s tricky to know for sure because there are so many things that can mimic MS, but the fact that you are having an MRI will go a long way to finding out one way or the other though - there will definitely be at least one type of scan done that is good for showing up MS lesions.
Things have changed a lot in 9 years - there are better meds, better therapies and better ways of diagnosing MS. So if anyone suggests that you don’t find out what’s going on, I strongly recommend that you tell them to take a running jump: 9 years is more than long enough to not be sure; time to get some proper answers!
Let us know what happens?
Karen x