Have you ever read the book redefining stuttering? By John C Harrison? It's free online as a pdf. He talks about your situational stuttering and fluency with old people and children in the book. And many other key things that one should know in order to become fluent. He is a fluent speaker now. His book has many accounts of people who overcame their stutter. I am actually going to implement what is said to do to become more fluent today. It's kind of scary but my own observations of the cure to blocking/stammering match up with his observations and truths. I can't deny what I know any longer because I keep coming back to the same truths.