@msgirl , the MRI is the primary diagnostic tool, but a negative test might not show the full picture. To be comprehensive, the MRI should cover the brain AND spine.
And there are different powers of the MRI scanner.
Even then, a negative MRI cannot eliminate MS as the underlying condition.
A Lumber Puncture, to extract some spinal fluid may provide further clues. As will an Evoked Potential Test which measures the speed your nerves respond.
You need to maintain a symptom diary (https://www.mstrust.org.uk/a-z/diary-symptoms), then you can create a concise list of your “clinical history” for your Neuro. This will provide other clues to your condition.