Affect of Pfizer vaccinations on Chemo treatment for advanced MS

I have been on retuximab (nurses call it “liquid gold” as it is rather expensive!) infusions every 6 months for 8 years to knock out my immune system. I was assessed at around 6.0-6.5 on EDSS.
In my 7th year, I had 2 AstraZeneca Covid vaccinations. I have an annual full body MRI and my neurologist compares it with the previous year’s MRI and also does a full neurological examination. There was no change year-on-year for 7 years.
Last year I had 2 Pfizer vaccinations. The check on my ankle, knee, wrist and elbow reflexes had only 1 positive result out of 8. My neurologist said that I had now got late stage MS (and also late stage Neuro Myelitis Optica, which is rare as hen’s teeth for a Caucasian male, so I’m on a global research programme).
She advised that there is nothing more that they can do for me now.
I have 2 questions:

  1. How long have I got realistically and
  2. Has anyone else had a similar reaction due to a Covid vaccination, where the chemotherapy no longer works?

Sorry to hear that dude