OP, honestly, I thought I could have written this myself.

First, how old is your child? They are much harder to take care of when they are younger but once they get past 5-6 they start to get a bit more self sufficient and things get easier. As you mentioned, they still have "new problems" all of the time. But that means they are growing and you are succeeding as a Dad. Good job :) Someone said to me "The days are long but the years are short" and it's very true. Once they reach age 7-10 they have their own friends and might start to prefer hanging with them. I know it sounds cliche but I miss hearing "Dad do you want to build legos?". Now I have to be the one to ask and I have a 25% success rate :D

I know saying that doesn't make it easier but hopefully learning more about who you are will help you learn who they are too. That to me is why I never stopped wanting to know who I was and why I had such a different experience. All so I could share everything with them and help them build a map for life as they got older. A map I never had.

I was diagnosed as "high functioning autistic" at age 32 and I can relate to a lot of what you're writing but specifically:

>I have approached problems methodically and functionally for as long as I can remember. I am infatuated with problem solving.

Once an interesting problem gets wedged in my brain, I walk through the rest of life spinning on this problem until it is solved or I am bored of it. My brain can even forget to eat and sleep when I'm focused. I learned that this is called "hyperfixating" and autistic people can be prone to it. I'm a dad of two kids and I do my best to be present and available, but as you mentioned, my brain is always tinkering on something in the background. I would try not to beat yourself up about this. What I've learned as my kids got older is that their brain functions the same way as mine. I may be trying to have a conversation and be "present" with them and all they can think about is the problem their brain is stuck on. For my one child, that might be a boss in Minecraft. I'll ask them "How was your school day?" and sometimes it will go ignored and they will respond with a minecraft related statement. That's ok :) I totally understand them now and don't take it personally that their brain is focused on something else.

>I find maintaining social interactions and simple friendships not easy and rather exhausting.

The last time I saw one of my friends was in April of 2022. I had a great time with him but I felt burned out after he left and had a hard time accepting invitations to do things for months after. It's not that I don't have a good time, it's that there's so much input and so many things for me to process that it takes me so long to bounce back. I have friends but I suffer from so much social anxiety that checking my texts or DM's on different platforms can overcome me and pause me in place before I get to respond. Then I'd suffer from the ensuing guilt of feeling like a bad friend for not behaving the "way I'm supposed to". When I have someone in the house who is not my immediate family(wife or kids) I am counting the minutes until they leave. It has nothing to do with them but everything to do with the fact that they are altering my routines and pushing things out of place later in the day.

I wish I didn't feel this way but it's been constant my whole life. I've always been extremely rigid in my schedule and it can cause great anxiety when people drop by unexpectedly and pull me away from something I was planning on doing. Anything that "interrupts" my plans can be emotionally hard to reason with. I eventually get over it but internally it feels so intense that it causes me to go nonverbal. Turns out this is another thing that folks on the spectrum can suffer from.

>Approaching strangers is extremely difficult for me.

I relate to...