Firstly, you need to see a Speech Therapist who specialises in stuttering. Learn proper fluency shaping techniques. Practice, practice, practice! Secondly, stuttering is NOT caused by anxiety or stress. But anxiety and stress can exacerbate it. The root cause is neurological, not psychological. There are just over 4.4% of the global population who have an anxiety disorder (approx 360 million people). They do not stutter at all. Only 1% of the global population stutter (approx 80 million). It’s deeply neurological. No amount of anxiety/stress therapy or anti-anxiety medication can cure stuttering.