A 38-year-old woman presents to your clinic 2 months after being laid off from her job following departmental downsizing. Since then, she reports persistent feelings of sadness, tearfulness several times a day, insomnia, difficulty concentrating on her job applications, and irritability at home. She denies anhedonia, suicidal ideation, psychomotor changes, or significant weight loss. She continues to attend interviews and maintain most daily activities but feels the distress is excessive and is worried she cannot cope. Which of the following is the most likely diagnosis?