Hi and thank you so much for your reply.
No, I do not have a Thai Bank account in my name, but I can open one the day I arrive. I would probably go to the Immigration office closest to Nonthaburi. (Do you recommend a particular office?)
I’m assuming the requirements for the 90-day conversion are not as expansive as the one-year extension - Visa Change Form TM87 marriage certificate, passport photos, US passport, letter from spouse, address in Thailand, flight tickets for end of 90 days. Am I missing anything?