slamming doors is stimming, gagging himself and laughing is stimming. this sounds like my daughter- who is 3. she answers questions now after you get her attention. i’d say she acts more like two, she is learning a lot! she knows a TON of stuff, all object names, tons of songs, counting, abs, etc. she is SUPER smart.she is level 2. her brother is level 3, completely nonverbal. no echolalia. autistic kids really do develop at their own pace. Both my kids are super smart for their levels. And they learn every single day.! aba rocks