@And***
your best bet would be to wring the 2 years of stay out of this visa by using it effectively.
Then when the second year entry stamp is winding down, (and seeing as you're in Chiang Mai) bounce out and back in at Mae Sai -Tachiliek border with Myanmar to get a 30 day visa exempt entry. IMMEDIATELY after you get that 30 day visa exempt entry go to the Chiang Mai immigration office and apply for an IN COUNTRY 90 day Non-O visa (based on having the required funds in a thai bank in your name), it will go under review for 21 days then you go back and get the Non-O visa, and a 90 day entry stamp inked into your passport. THEN you wait until you have 45 days or less left on that stamp and go back and apply for a yearly extension.
That is the way you need to do it, BUT you're a couple years away from that IF you work the current O-A visa you have correctly