not sure how to proceed

Hi and Welcome!

Although we are not doctors, we can often see the red flags of Autism to say, get your child checked. In this case I see enough going on with your description, that if it were me, yes I would do so.

My boys did quite a few things that your son is doing. The finger thing you describe my 10 use to do all the time lol. Or he would put his fingers together like an okay sign and it would stay that way for weeks.

So, imo I would seek the help of a Neuro-pyscologist, a pyscologist, or a developmental Pediatrician and ask for a full evaluation.

Make sure the Doc you find is an expert in the area of Autistic Spectrum Disorders because sometimes things can be overlooked that they don't see, or recognize but you see at home.

The list you wrote upbove is an excellent example of what to bring to your first Doc appt and if you can even catch anything on Video, it's even better.

I wish you the best of luck and keep posting and reading! Your child does not have to have a dx to belong here and you will soon find out that you have landed in a soft place that "gets it"

Lainie