Hi Kristina. As Darlene says there is a specific forum for TBI/PCS, lots of good information can be found there, as well as many folks who will relate and share their experience.
All brain injuries are different. Are you seeing anyone professionally for your symptoms? Speech or occupational therapy may be helpful. Another suggestion would be to have a neuropsychological assessment done by a clinical neuropsychologist; they can help identify specific deficits and recommending specific treatment. This can be expensive but health insurance may cover this.
All brain injuries are different. You are way too young to be a "lost cause". Best to you as you recover.