I can heavily related to this, while talking to myself or reading a book. I don't stutter, but when it comes to public speaking I stutter. It gets worse when I'm concious about it, and with each time I get more and more concious about stuttering, this stutter more. It's like a Paradox. I have been trying some meditation and it's helping a bit, ig. Anxiety makes you overwhelmed, thus making you lose control. My solution for this, is think better about yourself. Feel better, and meditate.