Based on the information provided, Quinn's symptoms and feelings suggest a strong element of anxiety regarding his future, particularly concerning his ability to graduate and enlist in the army. He expresses feelings of stress, a lack of control over his life, and fear about facing recruiters. These indicators align more closely with generalized anxiety disorder (GAD), which involves excessive anxiety and worry about various aspects of life.
While other disorders listed, such as major depressive disorder, can also involve feelings of helplessness and stress, the focus on anxiety about specific outcomes (e.g., passing English and graduating) leans more towards GAD.
Therefore, Quinn may be diagnosed with generalized anxiety disorder.