You being who you are is not a mistake or failure. Your thought process around this is probably a self fulfilling prophecy for anxiety.

I’m married to someone who has autism. She’s talked about it with me when we first got together years ago. She interestingly enough had a fake it until you make it approach. Before we got together she immensely researched facial expressions, nonverbal communication, confidence, appropriate communication, and some other stuff. She still has her doubts about her efforts but really they’re indistinguishable from people who don’t have autism when we’re in public. If you do want to change who you are for another person, which is a question you really need to think about, then maybe her approach may help. In reality after she got more comfortable around me, I love her exactly how she is without all of that.