My DS is autistic. He's also super smart, great company and an interesting, kind and loving human being. He has his quirks! But I wouldn't change him for the world.
Your DD does sound a bit like my DS when he was younger.
He's always much preferred the company of adults than children, and the ease at which he can talk to adults make some of them find it hard to accept he's autistic. They don't see how much he struggles (or, used to, anyway) with DC his own age.
He was always running off as a toddler and young child, I never got to sit and chat with the other mums, I was always chasing after him. (If I didn't, he'd just keep going and going! He really didn't care where I was!)
I suspected there was something different about him from a young age, but wasn't sure enough of my conviction, plus had some terrible advice from well meaning but ill-informed teachers and even a SENCO, and that stopped us going for diagnosis until he was 10. And by that point it was more obvious.
Your DD sounds lovely. She either is, or isn't autistic already. She is the same child you know, whether she's got ASD or not.
Have you heard the phrase, if you've met one person with autism, you've met one person with autism? It can affect people in myriad different ways. Some autistic people struggle to function in society without support. Others, like my mum, have fantastically successful careers - often in tech or the sciences which are full of ASD and ADHD people! (Many undiagnosed).
Sorry I'm rambling. I'm trying to say, I think you're right to be curious about whether your DD is autistic. But don't worry, even if she is, it's often not as scary as it may sound.
We thought a lot about whether to go for diagnosis and in the end we decided that especially as DS is a bright child, he deserved to have the words to describe what's going on in his own head. Which he now has, and he uses them well, he's able to explain to teachers why he finds things like metaphor difficult for example. (Not that they all understand!)