A good test is to take a sentence from a text and repeat it by mouthing it with no voice. If you do not stutter then you know it is not a problem in articulating the word. Usually it is a problem with consistency of airflow through your vocal cords. The reason why a fluent speaker doesn’t stutter is that they have consistent airflow. Checkout a book by William Parry where he talks about the Valsalva response as it relates to stuttering. This started my pathway to fluency. I am a speech pathologist and a lifelong stutterer. I have since transformed my brain from a stuttering brain to a fluent brain. I don’t stutter anymore and have never had a relapse.