Yes I also don't stutter when alone.. so that makes me believe it is all in my head. I always have this fear that someone will hear me stutter. So afraid to be embarrassed. Even when walking outside it is hard to pick up my phone because I am afraid someone will hear me talk. Now I try to challenge myself to just do it, even when riding public transport for example. But that fear always lingers around and I just can't get rid of it.