I’m exactly the same as you. I discovered that I’m stutter free while reading out loud years ago. I read a long passage behind a podium at church last week in front of a lot of people and I was 100% fluent. Also, when I talk to someone who is inferior to me, like a kid or a younger person, I’m fluent. However, if I sense that the other person has more authority over me, I tend to speak with a low voice and stutter a bit. One coping mechanism that works for me is to pretend that I’m reading from a pre-written text when I’m speaking to others