new to autism and cant find the appropriate advice

hi, I am new to autism so I am a bit lost. My son is 4 years old. He chooses not to communicate verbally although I know he is fully capable of forming words, maybe not long sentences. He chooses to spend most of his time alone in his bedroom, lost in his own world, playing with his cars, trucks and singing along to nursery rhymes on his ipad. He is a really happy kid, he only comes to me when he needs something which he will pull me 2 or bring to me.  He happily goes to school, although social interaction with other kids is non-existent. If another child tries, he will just move away. He will try to find small places he can hide in and play. He likes to run around in circles. Hes not violent, hes never shown aggression, he gets upset if doesn’t get what he wants but doesn’t cry much as hes easily distracted. Hes on the waiting list, but has not been diagnosed yet. I am still unable to potty train him, because he just doesn’t want to communicate.

I have been waiting over a year for a diagnosis, I thought I could get some advice online, but every page I visit, the type of autism being dealt with is the one where parents are struggling with behavior. Does anyone have or know of children in similar situations, am I over thinking and worrying too much? I know many parents have it worse, but I worry about his social wellbeing now that he is getting older and the fact he cant tell me anything.