Snoopy, my neuro said the same.

I do think I'm SPMS now. He still has RRMS listed on my records.
I don't think there's a specific thing they look for when changing your diagnosis. I think it's just an overall decline.
Mine told me that insurance doesn't cover much for SPMS so if you're wanting to try new meds usually your neuro would have to list your condition as RRMS.