I had my eldest son, LeeAnder, when I was 21; it was an unexpected pregnancy with a person I wouldn't have deliberately chosen to have a child with(he was an angry person, and became abusive over time).
I was 37 when my son Michael was born. In contrast my wife is a loving person. We had tried for years to have a child, before Michael there was a miscarriage, and my wife grieved over that child partly because she was so excited to have that first child, partly because I was the father of that child. Before we got married my father told my wife and me not to have a baby because in my family there was something mysterious going on with my brothers. Something was wrong and they were sent all the way to NIH in Washington to find out what was wrong. My younger brother had trouble walking, I remember and was angry at my parents constantly, and also timid about life. He couldn't relate to women, he never married, never held a decent job in his life, and mercifully died in 2010. My older brother when he went to graduate school suddenly broke down completely. He was very slow in everything, he drove me crazy! As life went on he became paranoid, had little in the way of jobs, and never married like my other brother. He couldn't relate to women, and yearned until the end to have a wife. He mercifully died in 2017.
My wife didn't want a baby originally, wanted to adopt, but I wanted a biological connection. To please me we had Michael. In the early years after he was diagnosed she was understandably upset. Now she's proud I'm his father.
We didn't really know anything was up until after age 2. He had some weird quirks; even as an infant, he'd fuss if a button on his clothes was undone, and as soon as he could walk, he ran around making sure all doors and cupboards were shut. He didn't play with toys, he played with spoons and broken phones. He didn't talk much. Occasionally, he'd talk a word or two. I remember hearing him say hello to the cat, and telling his dad this, but he didn't believe me. He could speak, he just chose not to, until about 7, when the wonderful world of politics fascinated him and he fretted to all who would hear it that the government was out to get his money. He's on the Asperger's end of things(though I don't think they use that term anymore). He had some OCD traits that got really messy. He about starved himself because there was always something wrong with his food. He would see bugs in it that wasn't there. He also got stressed over loud noises to the point that he would become violent. I remember he punched me in the back of the head once when I was driving because I was driving in the direction of town that had all the train tracks. He eventually learned to manage this fear, and we had his 12th birthday party at a park right next to the trainyard to celebrate.
When we travelled to Florida to see my wife's family we stopped on the way in Georgia to visit friends, and they had a young toddler who was speaking though he was 6 months younger while Michael at age two wasn't talking. I was alarmed! There were warning signs before this but I had ignored them. One thing I noticed about Michael was that he would run back and forth outside, apparently looking at his reflection in the windows. Up until even age 16 when he left us he would eat very limited foods. Any other foods was poison to him. This reminds me of your son son starving over unacceptable food. He only would drink water. Anything else he would make a face, then refuse to drink anymore. He twirled plastic lids on the floor. I should have connected that to the TV show where this young boy twirled plates. He didn't advance in how he played with his toys. He said a few words when he was 6 - 9 months, then he stopped. He engaged with us in a lively way, then it was as if he didn't have that life any more. It was less obvious then, but we have pictures of him that show that. It snuck up on us gradually. I have heard that autism sets in at about 1 year old.
Temple Grandin in an account I read also couldn't abide loud noises. Good to see that LeeAnder evolved to tolerate loud noises. Each autistic person is different, Michael wasn't like that.
I am ignorant about the difference between autism and Asperger's. I looked up descriptions of both and couldn't tell them apart. I saw a psychiatrist who was substituting for one day and his impression was that I had Asperger's. I hadn't even suggested I was on the spectrum. That is a sna judgement, however.