To the OP: Yep. I have a working vocabulary of a few thousand Thai words and can listen to Thai TV or overhear a casual conversation and understand what is going on. I'd rate myself at about 80% fluent listening and speaking. The compliment I get most from Thais is the sincere "You speak Thai very clearly" as opposed to the polite "You speak Thai well" offered to most attempts by foreigners.
I improve my vocabulary by about 3-5 new words or nuances everyday either remembered or spoken. Here in Udon, most of the new words are Isaan, not the Bangkok Thai I am used to speaking. I abhor Isaan language because it has a lot of nuances (slang) and the enunciation seems to change from person to person or area to area. I rate my Isaan listening at about 30% and speaking at about 10%.
To those thinking about learning Thai in Udon: Beware and be aware that you may be taught or inadvertently pick up Isaan words, not proper Thai. That may be fine for Isaan, but expect to be rebuffed or misunderstood frequently by HiSo Thais as you may unknowingly be speaking to them with a somewhat confusing mix of proper Thai and Isaan words.
Proper Thai is like an Englishman speaking English (dare I say also Americans?). Isaan is like an Australian speaking English (or whatever they call it - lol!)
