@TL *****
you are correct (you can't get another year entry stamp)
I beleive you confused the validity of the visa itself (which was a year from the date it was issued) with the validity of the entry stamp you got from the visa when you stamped in (which was valid for as long as your health insurance was up to a year)
You are done. that OA is toast and if you are wanting to get a year extension inside the country you need to have 800K baht in a thai bank account in your name only for 2 months before you apply AND you need to have the year 100K USD health insurance.
If you can meet the proof of funds, go to your immigration office and get the hand out listing the requirements for the year extension, get those together BY MONDAY <- the day your current stamp expires and go apply for a year extension at the Jomtien office for 1900baht