I recently did a ceu course where they talked a lot about the most recent research on the causes of stuttering. I would have to look at my notes for the specifics, but the gist of it is that stuttering is largely caused by discoordination, and that that happens most in 2 places in the brain: the cerebellum which is responsible for muscle coordination and the cingulate gyrus which is deep in the brain and includes the thalamus and caudate nucleus. All of these deep brain structures coordinate communication and emotional regulation along with a lot of other stuff. So, the thought is that if you can retrain your brain to better coordinate, stuttering will be less of a problem or not a problem. Also, the newest research about anxiety shows that pws (people who stutter) report that they feel anxious because they stutter, rather than the other way around. So there is some accuracy about what you said about being more fluent when you decide you don't care if you stutter. If you like, I can post citations for this stuff later.