Is your extension from Jomtien office and not some far flung province? This is one of the reasons people cannot do the next extension on their own.
Jomtien. I live in PTY
The other is that when you switch to non-O visa inside Thailand with a Pattaya agent, they get both the 90 day non-O and the 1-year extension all in the same day generally. And if both of those in your passport have the same date, every immigration office in Thailand knows you used an agent and will tell you to do so again.
I was already at the end of a 1-year extension. I did the non-O/extension by myself a couple of years ago, no agent. So I didn't switch visa types.
But in your cause if neither of the above applies, and you have the required funds in your bank account for the entire year previous, you can likely do it on your own next time.
Yes I have the required funds. I dipped below the minimum for a couple of weeks during the 2-month pre-seasoning, when my SSA was delayed, but had the full funds in my acct when I used the agent. I provided the agent with my bank statements
Thanks for your answers