@Adrian ******
, LOOK in your passport, if the stamp you have says "extension of stay permitted until" it means you don't have ANY visa anymore and are on an extension and if that's the case you CAN change the reason you have an extension (cancel the one based on employment and apply for a new one based on marriage) there is no "get a Non-O nothing in the process"
Take your thai wife to the immigration office (because those are the people you need to be talking to) and make sure they understand you DO NOT want a Non-O VISA, you just want to change the reason for your extension from employment to marriage to a thai