What Causes Dizziness And Poor Appetite After A Concussion?

Last January I got 2 really severe concussions that took me out of school and my normal routine for about 6 months. Since then I am constantly dizzy, my appetite has decreased drastically, my memory and comprehension is at the level of like a 6 year old, I always have a headache (especially when I listen to music or watch a movie etc) and I can barely make it through a full day of school. The last time I went to my neurologist, which was about 3 months ago, she told me that I should be 100% back to my normal self by now, but I am definitely not. Is this normal? It has been a year since the initial accident, how much longer should I expect to have these symptoms?