I'll address just one issue. I think I have addressed it before.

CTE (Chronic Traumatic Encephalopathy) takes time to develop. It results from multiple concussion but more commonly from hundreds and thousands of sub-concussive impacts.

It does not usually manifest until the 40's except for the rare athlete who has started their string of concussions and sub-concussive impacts at a very young age. With full contact sport sometimes starting at 6 or 7, some players subject their brains to high numbers of impacts before they reach their teens.

It does not sound like you are in this risk group.

Depression can be a part of PCS so you last question is not directly answerable. Anxiety about CTE or other issues can contribute to both depression and other PCS symptoms.

Those pesky little symptoms of aberrant thoughts and struggles are the main reason for improving nutrition. And not just taking a few vitamins but also avoiding substances that can be bad to the brain. Just because you did not have any head aches after drinking a few beers does not mean your brain was not effected by the alcohol.

The happy time almost sounds like a period of mania. I have had them but have never been able to identify what or why.

It sounds like you may need to think a bit more about lifestyle issues. Only you know all of the various behaviors that can contribute to PCS struggles.