@James *******
I would bet dollars to durian you have a stamp like this in your passport. You get it from the immigration office every year. It is NOT a visa, it is a yearly extension of stay and costs 1900baht, AND you also buy a multi-re-entry permit every time you get an extension and it costs you 3800 baht.
I can tell you have an extension and NOT a vsia because when you exit the country you are stamped in for the same date when you return.
Please feel free to help offer advice on the group, and know I meant no disrespect, it's just really really hard to fool me about visas or extensions of stays to thailand.
An extension and a re-entry permit looks like this.