Any hairdresser in here

I have a question my hair is falling out like crazy I know it's normal to lose hair everyday. But I brush my hair twice a day once in the morning and once at night and my brush has a lot of hair in it. I went to see my doctor and he said everything looks good. My blood work came out good. I don't really do anything to my hair it's always tide up due the fact I work with food. Sundays are the days were I get to do something to it. I normally let my hair air dry. I am over weight I eat some what healthy I don't exercise much I stress like normal stress. What am I doing wrong. Oh and I color my roots this gray hair has to go lol. And I can just pass my fingers through my hair and a fee strands come out. Any tips would be high appreciate it. Thanks ladies

Update: no birth control