I am no doctor, but from reading this it seems like you have a little bit of anxiety. Anxiety can certainly cause speech problems and difficulty in talking. But I don’t think what you have is an actual stutter. A stutter is an actual neurological condition where your brain physically has trouble producing certain sounds in words and blocks the airflow needed for you to produce speech. I am someone who has a stutter and even when I am by myself and very calm, I still have a hard time talking and producing sounds. My advice to you would be to try to seek some help for your anxiety or try some meditation. I think if you can reduce your anxiety and stress levels, you will see your speech start to get better. Best of luck to you