What is the main conflict in Catalyst by Laurie Halse Anderson?

The novel Catalyst by Laurie Halse Anderson is a tale of teenage growth and coming of age. The protagonist and narrator of the novel, Kate Malone, is an eighteen year-old senior at Merryweather High School. She loves math, science, running track, and is fiercely loyal to her family. Her father, Jack, is a reverend; her brother, Toby, is fourteen. Kate cares for them, doing their laundry and making sure they take their medicine and eat well. Kate's mother has been dead for nine years, having died of sudden pneumonia.