Starting with your doctor is great step in getting some of your concerns addressed.

The MCHAT-R is a helpful online tool in assessing if your child may be on the autism spectrum. If the tool determines that autism is a possibility, it will construct a draft letter to your doctor asking for a referral for an autism evaluation. You can also simply ask your doctor for a referral.

Click here for the MCHAT-R tool: https://www.autismspeaks.org/what-autism/diagno....

For more information on what the MCHAT-R is and how doctors use it, see: https://www.autismspeaks.org/science/science-ne....

It's hard to say, I'm sure when they do the assessment with therapists and possibly a psychologist, they will be able to identify symptoms by actually being in his space and observing him. Often times when we are told the word "autism" we start looking and finding symptoms straight away that may or may not be actually part of the diagnosis. I did that with my son! I would note these things down and when they ask you questions.. and they will be asking you A TON, answer them honestly. They will be able to confirm a diagnosis for you! :)

Definitely autism he might be low functioning or high functioning how old his he

It’s possible that these can be signs. Thankfully you have an appointment coming up so you can tell the doctor your concerns.
Some of the things that I saw in my daughter that led me to get her evaluated was difficult in transitioning to something new. She was saying a few words then stopped & didn’t say anything at all. She did not play properly with toys & the biggest one was not responding to her name.