Being in California means you can get State Disability. This can be helpful. The Calif State Disability office may be able to give you some help about protecting your job. California has many ways it regulates what an employer can do beyond federal FMLA.

Is there any way you can stagger your work shifts to 12 hours on then a whole day or day and a half off? Working Monday night then Tuesday night off then Wednesday night on then Thursday night off then Friday night on, etc. The 36 hours off between shifts may give you enough time to rest up. Your time off should be focused on getting rest.

When I was in the early months after my injury, I could rest up in advance of a stressful task/event. I could accomplish the task then rest up afterward.

There is no way to compare your injury to others. Everybody has their own limitations and capabilities. It is a futile and anxiety producing effort to try to plan your recovery based on the recovery of others.

I wish I had better words for you but concussion is just so variable.

My best to you.