Forgotten & Found- a 5SOS fanfic

Running away is hard for most people. I ran away from a perfect family, they just didn't love me. The only one who loved me was my brother. I told him, I have to go, I can't stay where I'm not wanted. We spent one last day together before I left. We packed my clothes that day, and said our final goodbyes. I left that night, before I left I told him "Don't forget me cause you know I might forget you," he understood, then I ran. I heard him sobbing all the way down the street, I ran to my best friends house, and told her to take me away from here. We drove, and found a nice apartment and got jobs. Then, she left me. she left me in the streets. That was 2 years ago, now here I am in an ally, I can't remember who I am, or where I came from.

I can't remember anything.

Why can't I remember anything?