I'm the same, although I'm only 27. I've just already had a number of negative experiences interacting with people and them reacting ignorantly. It has even costed me at work (it was clearly a factor in why I was let go from my last job) and I've even been falsely accused of being overly intoxicated at a few places. I've had people encounter me stuttering and from that they write me off as if they know my entire life and my being as if it was one-dimensional. As if I'm supposedly less intelligent, less capable than they are. I now don't expect people I don't know to be understanding of it unless they prove so genuinely, so I now don't tend to speak to most people unless it is necessary, especially at work.