It is a spectrum, and there are plenty of people who are on the mild end of it. I told my son that whatever he's got, I had it too, it just didn't have a name or diagnosis when I was in school.
My son also had peripheral vestibular disfunction (PVD) which effected his balance and motion, so he didn't learn to ride a bike until he was 10. He also had a lot of anxiety that came from not being able to hear or do things on the first few takes, and not responding to people unless he was looking at them. His school was actually pushing the autism diagnosis, but when we had him tested, he came back as having ADHD. I was surprised, because he is the opposite of hyper and about as physically active as a house plant without external motivation on my part. I was loathe to put him on medication, but he came home one day very upset with himself because he knew he needed to be focused on math but just couldn't stop thinking about Pokemon. One week on low-dose ADHD and he was noticeably happier without any other changes in his mood or behaviors. He went from failing all of his core classes to two consecutive years on the school honor roll, in middle school. He's got total control over when he takes his meds, knows what they do and their limitations, and only takes them when he needs them. Having seen what they have done for his quality of life, I am now a believer that they at least worked for him. Some of that comes from a very different structured learning style that I inflict on him - he once told his teacher that I teach math the Navy way, which is repetition and yelling. But it worked, and in conjunction with the medication, he has become much more resilient and capable of doing unpleasant and hard things when called upon.
All of which is to say whether it's autism or any other issue, there is a lot of support available and every parent wants their kid to be reasonably happy and successful. So kudos to you for trying to nail things down and set her up for success during some of the most difficult years of adolescence.