Propranolol (beta blocker) will help. It shuts down the fight or flight mechanism in your brain. It calms your voice, your heartbeat and your nerves. It's really amazing...
https://www.consumerreports.org/cro/2012/04/can-you-treat-st...
I pop 4-5 of this 1 hour before a big meeting or presentation. I've also used them at private gatherings when I'm speaking in front of a larger group. Works really well. Tell your DR about your public speaking fears and he/she will more than likely prescribe you a beta-blocker.