Your neck could be a trigger for your headaches. But, if you can write War and Peace, it appears you are doing OK. It is too much information and overloads me such that I struggle to sort through it to understand what is going on.

Lifting weights tends to cause a lot of muscle tension in the neck. Maybe you need to try to find somebody who can assess your neck and help you relax the muscles.

There are many different protocols for upper cervical therapies. Chiro has half a dozen ICA Council on Upper Cervical Care - Diplomate Program

Some osteopaths are good with upper necks. Some physios, too. You just have to find the good ones. It can take a lot of visits to find the right one.

The propranolol success suggests it is a blood pressure issue. Brain stem concussions/inflammation can cause disregulation of blood pressure.

It sounds like you just need to try different protocols.

My best to you.