I think I'm autistic
Were you diagnosed by a doctor?
No, people don't understand me and they think I'm just weird
A lot of us are just naturally eccentric and socially awkward. That shouldn't make you assume that you are autistic, though.  People who truly have autism have a very hard time, so it is important to get a real diagnosis.
Why does it matter? They're weird so I am.
Being unusual doesn't mean you're autistic. You should read and learn about autism, it's not correct to assume being weird is same as being autistic.