Anxiety or overthinking can do lots of weird things. A lot of people report lessening or even overcoming their stutter after overcoming their fear of speaking - their fear of stuttering. Im the same. In privare 100% no stutter, yet in front of humans, I stutter. Ive been working on learning to overcome my fears, and to stutter in front of people willingly, to overcome my fear for that. I'm now at a point where my stutter is wayyyyyyy less, because I care so much less about other people hearing it now. Imo its a crucial aspect in overcoming stuttering. Wish I had started doing this many years ago. I was also the type that blamed stuttering for ruining my life, instead of looking deeper, realizing anxiety was at the root of this problem. Hope this helps!