Confidence comes from within therefore to be it you must find it in yourself to be realistic and say “fuck it if I stutter I know it’s bound to happen I can’t change that but that will not stop me from speaking anyways”. If you constantly embed some type of positive affirmation or mantra into your mind you will develop confidence overtime. Take pride in every word you say even if you stammer will exude so much confidence to the other person even if you feel insanely insecure in that moment. Look at it like this you know you have trouble speaking and for you to continue to do it even tho it makes you insecure shows how bold you are it takes courage to wear your insecurities on your sleeve my dude for most people they can hide there’s WE STUTTERS CAN NOT! that alone should make you feel mildly significant.