I've only recently come to believe that I have AS, and if I do, it's pretty mild, especially in the "how to act around people" realm. Then again, I have avoided social interactions for such a large chunk of my life at this point, that I really don't know. I think I come across as a quiet, 40 something woman. Who knows, though. Maybe I seem weirder than I think. That would explain why people treat me like I'm invisible a bit more often than necessary.
So, I never had any concrete feeling of trying to act a certain way (aside from high school when I tried to be Stevie Nicks). However, one incident does come to mind. About twenty years ago I had a best friend who was extremely social and outgoing. We became friends because she literally came to me when I was brand new in the area, and said, "Come with me. You and I are going to be friends." She was my safety net in the social world, and for her I was a kind of respite from all that stuff, and we were best buddies for years. Well, at one point, we worked at the same building, with the same people. She was so outgoing, and would walk into a room full of crusty old men, and say something like, "Howdy, boys! How'd y'all get so handsome?!" with a kind of southern charm. They loved that. Then one day, like an idiot, I attempted to say something similar. The room went quiet for a while, as everyone just looked at me, and then someone said, "What possessed you to say something like that?"
I guess I could name other incidents like that. I never thought of it as trying to be NT, but as trying to just be something I'm not.