I am also at 13 months for a mild concussion that has left me out of work and un able to do many of the things one normally does in a day. I had been doing much better until some recent testing that found some inner ear damage, but stirred up all my symptoms again. I have not gone a day with out a headache in all that time. My neuropyschologist said "some day you will leave here and not be crying".
I am told that I still have a chance of recovering better than I am now. It just takes time.

Every person is different and every body heals differently, you will feel better, I still hope to!