Haha, that's me!
The good news is that now that I know I have AS, I just tell people right away, "I always look nervous when I'm relaxed and my voice often sounds shaky and emotional when I'm not feeling any kind of emotion."
Fortunately, so far, everyone has accepted this explanation and many seem grateful that I told them. My boyfriend said he even explains it to people before they meet me, probably something like, "She has this one quirk - she always looks tense even when she's completely relaxed and her voice often sounds shaky or intensely emotional when she's not feeling that way at all." He told me he thinks this helps people to understand and relate to me better, so I appreciate it. I mean, it must be working because all of his friends seem to like me.
I could conclude from this that I should just go ahead and tell everyone I have AS, but that's a big label with a lot of associations attached to it, making it hard to predict how people will react.
It's amazing that simply explaining my AS characteristics, individually, is so simple, easy, and effective!