The main character is a girl, she stays in her house 24/7 because she has trauma from a school shooting and has flashbacks but she has been working toward going out of the house. She starts on her front porch then gets further etc... She gave the shooter a ride to school that day and when he was shooting he recognized her and spared her.

I would have read it around age 14 in 2014. It was probably a little dark for my age but I like those kinds of books. It was definitely young adult. It was average length, not long but not short. I dont think it was new at the time. I think the title was short and I cant remember anything about the cover. I borrowed it from the library.