Hey mate if you don't stutter alone then this is 100% curable and it's just a neurological pathway problem. Your fight , fright , flee response gets activated when you talk to strangers and thus resulting you to perform a bad motor response it's called "valsalva maneuver" this needs a a lot of training to correct it. But once you get this it will be perfect. One thing try using a false voice like using a different pitch voice while talking as if you're mimicking a movie / cartoon character. And use their exact speech expressions this will reduce ur stutter to 50%. Using deeper voice is preferred as it looks more natural than the high voice. Buy the book I mentioned above you won't regret. I can say i am 90% cured bruh. And all those doctors who say this can't be cured are just fuckers providing false services just so that people would pay them for attending their sessions regularly. this is why no person in the world has ever been happy with a speech trainer/pathologist or any other. And ultimately realise they were burning money to light their lamps. I really wish you bright future. do check all the sources I mentioned. And i stutter a lot in front of my family especially my dad but not infront of world anymore.