Could my son be autistic?

My autistic teenager came up to me the other day and said she believes there is 'something wrong' with her brother. Ever since he was born, she has always said this and has had a hunch and actually talks and behaves with him in a way I never would expect her to. She's great working with children but this is something different. She has so much patience with him and is so observant and has actually found the underlying issues when he misbehaves. She says 'Behaviour is communication'.

He is an 8 year old boy and still does wet the bed every night, and sometimes during the day. He eats things which arent edible, paper, cardboard, tissue, grass. He does have some issues with behaving and listening. We do have professionals involved and the school are working with us. But it is what my daughter said, which I can't stop thinking about. He does show some of the same signs of autism that my daughter showed at a younger age but also signs of ADHD which my daughter also showed. Its a little confusing and sorry if you don't fully understand.  

My daughter has many strategies when with him and ways to help with his behaviour and has done many things in the past to help. She is the best with managing him when times are tough and he shows challenging behaviour. She is very caring with him and overall is great with kids. Could my son be autistic or have ADHD or is this just my son? My daughter is really making me want to ask and answer a lot of questions. 

Thanks for reading this. I really appreciate it.