How can I secure a one-year extension on my Non-Immigrant O Visa in Thailand before traveling in February?

Note that 17 & 18 Feb is a Saturday & Sunday so immigration offices will be closed so a bit tight unless you are certain you have everything immigration requires

Your embassy is correct. Only a couple embassies now sell the year/multi Non-O based on marriage

Be that as it may

𝗪𝗵𝗲𝗻 𝗱𝗼 𝗜 𝗴𝗼 𝘁𝗼 𝘄𝗵𝗶𝗰𝗵 𝗜𝗺𝗺𝗶𝗴𝗿𝗮𝘁𝗶𝗼𝗻 𝗢𝗳𝗳𝗶𝗰𝗲, 𝘁𝗼 𝗴𝗲𝘁 𝘁𝗵𝗲 𝗼𝗻𝗲-𝘆𝗲𝗮𝗿 𝗘𝘅𝘁𝗲𝗻𝘀𝗶𝗼𝗻 𝘄𝗶𝘁𝗵 𝘁𝗵𝗲 𝗹𝗲𝗮𝘀𝘁 𝗵𝗮𝘀𝘀𝗹𝗲 (𝘄𝗮𝗶𝘁𝗶𝗻𝗴 𝘁𝗶𝗺𝗲)?

you don't get to pick and choose what office you go to for your year extension. You use the office that serves the area where you live AND where you have the TM30 filed (which you will need to file once you get here at the office in your area)

You can apply for a year extension at MOST immigration offices when you have 30 days or less left on your current stamp.

You will apply for the year extension for 1900baht and get a 30 day under consideration stamp.

THEN on that date you'll go back to the immigration office and get the year extension inked in and buy a re-entry permit at that time.

Using your time line, IF you arrive on Nov 23 you will get stamped in until Feb 20th meaning you could apply for a yearly extension any time AFTER January 20th..

SO that means

You either apply for the year extension for 1900baht BEFORE you leave the country on the 4th of Feb. You'd get the 30 day under consideration stamp and you'd need to BUY a single re-entry permit for 1000baht so you can get back in without cancelling that stamp

OR

You buy a single re-entry permit for 1000baht and leave the country and when you come back on the 16th you get your act together to apply for the year extension BEFORE that 90 day entry stamp from the Non-O you have expired (the 20th of Feb)