That's like my ASD-like daughter --- possibly me. I kept telling my mom how expressionless my daughter was and she would say --- "no! look at her bouncing around, smiling" (and flapping). Me: "Oh, yes, but the OTHER times..."
I feel big, and emotional regulation is difficult for me (duh, ASD). That said, I learned that big happiness is more acceptable in the NT world than big sadness --- so I "let" happiness out, and suppressed the sadness (which I expressed through self-harm in my youth). That said, I've been yelled out for "too much" happiness.
In my ASD group I can express more of my big feelings and it's taken in stride. I mainly (big) happiness and (big) sadness. I still stay away from anger which feels taboo, although others express it in our safe place.
Yea for a good friend! I am fairly certain my BFF is Aspie, but she's not interested - perhaps just a lot of traits (BAP). She has stims, but says they are not stims, etc. Oh, well. And I don't want to "pathologize" her. For me knowing doe myself is freeing - I guess she sees it differently for herself.