Anxiety is a modulating factor in all stutterers. Take modulation to mean multiplier. There is still the underlying condition, i.e. the base that is being multiplied. People who do not stutter may experience similar levels of anxiety but not stutter because the base is 0 in their case. You don't have a psychological stutter, but your stutter may have psychological manifestations. It is important to make this distinction because if you are convinced that your stuttering is psychological and you blame anxiety for it, you end up even more anxious and in your head because you try to control your anxiety. If I tell you don't think of an apple, you think of an apple. If you tell yourself don't be anxious you become anxious.