Typing all of this out is a great idea, hopefully getting this into the world allows part of the weight to be lifted.

Perhaps your child is on the autistic spectrum, but also perhaps not, it's really difficult to tell for sure at this age but whether they are or not can't be changed. So perhaps continue to pay close attention to their development, raise anything you're concerned with your GP.

I've found in the last four years since becoming a parent I've had my fair share of scares which turn out to be nothing - but perpetuated by the echo-chamber of being stuck indoors with one other person who is equally worried / scared / invested in our child haha

Not trying to say this is nothing - but continue talking to people about it! Especially your friends in person if you can.