Woow thank you for the comment. Lack of confidence during speech is not related to lack of confidence in general. It is more attributed towards public fear. May it be an audience of 20 people or 200 people.
I can see your one on one conversation skills are great since you are in the marketing business but presenting your point of view to an audience of a group of people is a bit different.
What you need to do is start from the basic. Give a presentation to an audience of 4-5 people (preferably your friends), see what you are doing wrong and correct those mistakes.
From what i can understand is that you just need to get out of the shell.. and you will be good to go..
And no problem if you didnt upvote it. I understand the requirement of powering up ;)
Kindly consider to resteem this instead of an upvote :)