Another one who prefers to use 'Aspergers' and I often refer to myself as an Aspie. I think it's a lot less austere than 'Autism' and I find that NT people tend to react less frequently like you've just announced you're a serial killer if you refer to Aspergers rather than Autism.
I don't really mind telling people about my diagnosis if I think it's relevant and there is a purpose for doing so, but I do get plenty of 'Oh, I'd never guess", or "You can't be!!!", and I think that's because a lot of NT people are still under the impression that all autistic individuals are either as dysfunctional and fragile as Raymond from 'Rain Man', or act like simpletons and behave like Forrest Gump.
Even my own mother is sceptical because I didn't particularly display much in the way of common autistic traits as a child, but I've had practically no relationship with her since I was a teen. I never spent any typical family time with her as a child anyway, and she'd never seen how I live as an adult. She's really not in ant position to diagnose me, despite being my parent.
This is the crux of the problem as I see it. Too much ingrained belief that all autistic people are either the same, share common traits, or can be spotted a mile off because we stand out like a sore thumb. It's simply not true. We're as varied from one to the other as NT people are, and it's often only the people who are around us constantly who actually notice our autistic behaviours or witness the meltdowns and stimming.
I have absolutely no problem interacting with strangers, meeting new people etc, yet my partner says there are days when I never look them in the eye at all, even though I'm not aware I'm doing that, and I literally can not look at portrait photographs of close relatives without becoming extremely uncomfortable and looking away. Go figure.