Hi there
For a stressed out 14 year old with a brain injury you articulate your situation, feelings and symptoms in a way that I can totally relate to.
It's frustrating, scary and confusing times - we've all been there. I remember in my early stages (and still now) I desperately wanted to just understand and be understood! It's such a foreign weird feeling, but we have to trust that it's all part of neurophysical damage from the injury...not that we're just going crazy. It's a complex world up there!
All injuries and resulting symptoms are highly individual but there's a lot of commonalities too. I've experienced what you explained too. Remember, you're not alone!