I was you - 2 years ago (in 17 days from today).
I knew something was different about Kieran, but I thought he was fine. He was my first, I had nothing else to go off of. He was hitting all the milestones (except speech) that the nurses gave me the sheets for.
But he wasn't talking - he was biting. He was 2 and had VERY limited language and bad outbursts. I thought he had good eye contact, turns out that was only with me, so I never noticed him not looking at others.
I had to fight to get his diagnosis, but at 3 he was dx with autism.
The evaluation is not hard, but it can be emotional. For us, it was a 2 day evaluation. First day, for a few hours, he was seen by a physcologist and a GP, and a speech therapist. Second day, they watched him play, then he was seen by an occupational therapist and the GP again. Then they all met, and when we came back, we were given the dx.
For your own piece of mind, do an MCHAT screening, it will give you an idea of if your child has signs or not.