Slow Cooker Cheesy Chicken Rotini

Chicken breast (boneless and skinless, 2 large)

Cream of chicken soup (2 cans (10.5 oz each))

Chicken broth (1 cup)

Pepper (1/4 tsp)

Oregano (1/2 tsp)

Garlic powder (1/4 tsp (or to taste))

Onion powder (1/4 tsp (or to taste))

Sour cream (1 cup)

Shredded cheddar cheese (2 cups (divided))

Rotini (1 pound)