I have the same thing bro, our minds work so fast we already anticipate the block and that is the thing that makes us block, when you're not thinking about like when you're talking alone you don't or rarely stutter. The good news Is this proves its a mental thing, my dad and even 12 year old cousin stutter but they never cared about it so now I rarely hear it and if they do stutter no one cares since they don't care. If you wanna chat I'm here eventough I'm only a highschooler.