I am the same way, I can have a full on conversation with myself like some crazy person, and not stutter once. When I get around people I start stuttering. Like I said in another post, I feel part of it is yes being comfortable but also your brain is now programmed to automatically assume judgement from people when you start stuttering. I know when I speak to someone for the first time, and I start stuttering. I get looked at like someone just saw bigfoot for the first time. Basically what I am saying it's like your brain is I default mode, and you need to get it out of default mode. I served in the military, and I know it's possible to teach yourself and your mind new things. Military for example everything you know, and do is wrong when you come in. They teach you how to Eat, Shave, Shower, Time Management all these things. They have now programmed your mind to do things way different than what you are used too. Hell I still eat fast to this day, and live how I did in the military. So if we can figure out how to take our minds from default, and reprogramme certain things. I'm not saying it will cure our stuttering 100 percent, but it may help it improve.