Chicken-Orzo Soup

1 (32-ounce) container fat-free, less-sodium chicken broth, divided
1/2 cup uncooked orzo
2 tsp olive oil
2/3 cup coarsely chopped carrot
1/2 cup coarsely chopped celery
1/2 cup chopped onion
3/4 pound skinless, boneless chicken breasts, cut into 1/2-inch cubes
1-1/4 cups water
3 fresh parsley sprigs
1 fresh thyme sprig
4 cups fresh baby spinach
1 Tbsp fresh lemon juice
1/4 tsp salt
1/8 tsp black pepper

Bring 1 3/4 cups broth to a boil in a medium saucepan. Add orzo; cook 10 minutes or until done. Drain. While orzo cooks, heat a large saucepan over medium heat. Add oil to pan; swirl to coat. Add carrot, celery, onion, and chicken (I just added my precooked chicken at this point); cook 3 minutes, stirring constantly. Stir in remaining 2 1/4 cups broth, 1 1/4 cups water, parsley, and thyme; bring to a boil. Reduce heat; cover and simmer 10 minutes or until vegetables are tender. Discard herb sprigs. Add orzo, spinach, juice, salt, and pepper; simmer 1 minute.