OP, try not to make, or listen to, too many assumptions.
Children with ASD can be very, very different. There isn't a rule that they all follow.
It's really good that you have identified that he may have ASD early on. Interventions work better if they are in place early.
Nobody can look at a snapshot of a child and say whether they do or don't have ASD. Diagnosis is a long and complicated process that usually involved a number of professionals from different discipline spending time observing the child, talking to you and then comparing what they have recorded against the diagnostic criteria.
You DS is a long way off from an autism diagnosis just now. However, he may have a neurodevelopmental disorder and identifying it now would be helpful to him.
Go to your GP and ask for a referral for a neurodevelopmental assessment. You aren't asking for anyone to diagnose him. You're asking for professionals to assess him, identify any additional needs he may have and make recommendations for supporting him.
I have two DDs with ASD. They were diagnosed at 12 and 7. I wouldn't change them for the world. If your DS gets a diagnosis, it won't make him any different from the gorgeous little boy you cherish right now.