Do I have permanently damaged hair and will it grow back?

About 9 months ago i went and had my hair bleach. About a week later my hair started falling out in clumps. It did not fall out at the root but mid shaft mostly in the center of my head. i havent dye or used any heat on it since because ive been afraid i would lose more of my hair. Ive been waiting for it to grow back but after all this time some of my hair keeps growing like normal while the center of my head where i suffered most hair loss has not grown at all.