Hair falling out? Anyone Else

Kimberly
So I'm 19 and my hair falls out in large amounts (seems that way to me). I started noticing it around 15/16 when I was on pill. I read that hair falling out could be a side affect. It's had gotten so bad that I stop taking the pill around 17. At first it seemed to be the culprit because I would only lose a few strands but now I'm losing a lot again.  I have thick hair and it's not noticeable that I'm losing my hair but I'm wondering what it could be. Any suggestions? 
From top to bottom. Brushing my hair before I shower, the hair I lose during my shower, and brushing my hair after I shower