(((NightFire)))
You aren't crazy, no. Of that, I am absolutely certain.
You have been dealt a very heavy load of physical (concussion) and emotional (the death of your twin sister) trauma. These two issues alone are HUGE!! I can't believe that your father is being so pushy and demanding that you get to work on your studies.

I can't understand what his motivation is for being so rigid with you. Maybe he's trying to cheer you up with getting you to focus on your studies???
Do you work with a T for your severe clinical depression, OCD, anxiety, and ADD? I take it that you are on medications, to try to manage these issues? I hope that you do! I would recommend talking to him/her about this issue and get their professional opinion on what you can do or say to help your parents see that they need to back off you a little bit, but still show that they care about you.
If you aren't seeing a T...that's what you need to do asap. Gaining some tips/techniques on how to work through these emotions, especially as you are recovering from a TBI (traumatic brain injury). You can't get through all of this mess without the support and tips from others. You need as much support and consistency as you can get ~ because that's what helps us get into a stronger state of mind.
I had a TBI in 03/08, along with all of my mental issues as well. I recall how difficult basic things were for me...for a couple of years.I still require assistance every week to help me plan things and make certain that I'm going to doctor appointments, seeing my nurse, etc. I'm not saying that you require the same assistance ~ what I am saying is that you do need emotional support (and sometimes physical assistance). Perhaps if you were to present the issue this way to your parents they would be more empathetic and supportive towards you.
I hope so ~ you're in my thoughts!