How can I obtain a yearly extension for my Non-O visa as a spouse in Thailand?

You would take documentation from your husbands place of employment stating it's okay for you to be "piggy-backed" onto his yearly extension (get an extension of stay that matches his). Then you take the marriage certificates, and documentation from the company your husband is employed at to the immigration office and apply for an extension of stay that matches your husband. There is no proof of finances when getting that extension. But it does require documentation from where your husband works. I'd check with the company he's employed at and see if they can contact the immigration office to get the list of required documents for that extension.

ONCE you get the extension that matches your husbands, you can apply for a multiple re-entry permit so you can come and go all you want and keep the extension date valid when you return.