It is hard when people don't understand why you're leaving parties early or they think your kid's a brat and you're just a poor parent. It can feel isolating.
I know other kids think my son is weird. He has been bullied at every school he's attended. He never tells anyone, other kids report it. When we lived in London, he went to an international school and two kids peed into a pop can and tried to get him to drink out of it.
I knew something was up when he was about 1.5-2 years old. He *never* napped. He liked to line up Matchbox/Hot Wheels in a long line. Once, our dogs were playing and displaced a few of the cars. The way he screamed! We were living in an apartment in the city and I was worried someone was going to call the cops. At Test Track, he would just want to sit in the post-show cars and get excited when a "new car" was revealed on the platforms. He did not want to leave. He would rattle off all the makes and models of cars. I would think about autism, but he was hitting developmental milestones on time. He was in day care and one of the teachers noticed other things, like repeating himself over and over and not making direct contact. He was four at the time. We were able to contact the school district and get him assessed. The psychologist diagnosed him with AS and he started "early childhood intervention" and he spent the mornings getting different therapies at the school, then a bus would drop him off at day care in the afternoon. I am really grateful that we had access to these therapies through the school district.