While symptoms that improve while one is relaxed is a sign of TMS, please know that consistent symptoms do not disprove TMS -
it is still very possible for something that does not appear to wax and wane to be TMS. I had an endoscopy with scalloping and other signs of what was sure to be disease (including very red mucosa), only to be told nothing was wrong (and that indeed turned out to be true, as opposed to a medical oversight). Sometimes something we feel very strongly about isn't what we think it is, even if there's evidence.
Studies have shown that festinant gait can sometimes be caused by anxiety in Parkinson's, and if that's happening to Parkinson's patients, individuals with "functional disorders" are definitely going to be subject to similar symptoms:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4175083/ (Does Anxiety Cause Freezing of Gait in Parkinson's Disease?)
In fact, here's information specifically on psychogenic movement disorders - note that gait issues and other symptoms similar to Parkinson's are referenced, so individuals with "functional disorders" ARE in fact experiencing these symptoms:
https://www.bcm.edu/healthcare/care-centers/parkinsons/conditions/psychogenic-movement-disorders (Psychogenic Movement Disorders)
Some interesting tidbits from the second article:
So even though you are experiencing these symptoms, it doesn't prove that you have Parkinson's. And even if someone did have Parkinson's, anxiety can still be a major culprit behind the symptoms. Your MRI being clear was a major step in figuring out what's going on.
My advice is to call your doctor and find out the date of the DaTscan or schedule it today if it hasn't already been confirmed. No matter what happens - regardless of the diagnosis - there is always hope. How are you coping with daily life right now? Is there anything that helps you feel better, even if only for a little bit?