I guess what you describe applies to most people who stutter. Stuttering causes a withdrawal from social interactions and then a lack of social skills. Especially in larger groups. I personally do fine with only 1-2 people. With more people around it becomes more difficult and I become more and more quiet. The good side is, social skills can be learned at any age. But I don't have any advice on how to do it . Except jump over the fear and embarrassment and just do it