So you have a Non O visa, based on marriage.
Then yes immigration would make you obtain the first extension to be based on marriage.
Pity as you have the funds in place for extension based on retirement.
Suggest you contact an agent after arrival or now using their contact options.
In previous post I included link to post from Tod Daniels. Lists contact details for Pattaya agents.
You could start with Maneerat.
Alternatively enter on the e-Visa and be stamped in for 90 days.
For return (next trip) get a new Non O retirement.