I went to immigration in Jomtien. They accept a proof of monthly transfer, of minimum 65.000 bht. If stated by bank, over the last 12.000 bht. Then no month can be missing though. I asked, because I am tired to hold 800.000 in bank.
Relax. All too soon. And indeed it a question if you have to fill in a tax declaration as you probably be exempt. Once it is clear you see your answer everywhere on the net.
You not give enough detail. The nationality of your girl, can be a determinate factor. Philippine stay here with bf, or to work, and do all tricks to stay as long as possible.