End of the World - Lissa Lores

When Charlie was 6, she was adopted out after her fathers death.
She left her two brothers to move in with a family.
. 5 years later, the apocalypse started.
She had a camp. A family. She and her friend Sam are sent out on a mission, which takes them from Virginia all the way to Georgia.
Something goes wrong, and she's stuck, all alone, injured and afraid. Then, a group finds her, and changes her life.