Here's a way to tell whether your stutter is psychological or structural (i.e. a problem in your brain that you can see on imaging): Go some place where no one is around and talk to yourself out loud. Try to repeat the same sentences you stuttered on when on front of people. If you're most perfectly fluent, then it's something psychological (like most of us). If it stays exactly the same, then I would schedule an appointment with a neurologist right away (depending on your country, you might have to see a primary care physician first)