I'm not trying to minimize your experience. But here's the thing: unless someone tells you their stereotypes about stuttering / anxiety / whatever you don't actually know that person's stereotypes. If they do hold negative stereotypes about stuttering (or any other feature for that matter) and act on them then, yes, we may likely experience tangible detriment. But if they don't express their stereotypes we don't know whether they have them or not. In this case any reaction we have to potential stereotypes is "mind-reading." Thus, any blow to our "confidence" is not based in reality. It's our catastrophizing the situation, or attributing thoughts to the other person that might not exist. And so, in the absence of tangible expression of bias against stuttering the beliefs of other people do not have any bearing. The beliefs of other people are like Schrodinger's cat. Until we know what they are they are both positive and negative with regard to stuttering. And therefore are moot.