You get expectation anxiety from the attention being pushed to only you, how to escape it is to actively focus on your mouth, stiffen your below and speak with emotion, for me atleast. The solution would probably be to pin down what exactly about those encounters trigger that sensation, is it the eyes on you? the thing you have to say being most important? what exactly is it? When you've figured that out, start interacting with people and putting yourself in that situation to see what works.