Healthier Shrimp Gumbo from Food 52

Name: Healthier Shrimp Gumbo from Food 52
Ingredients: 2 tablespoons grape seed, canola or vegetable oil; 2 tablespoons all purpose flour; 2 large onions, chopped fine; 2 stalks celery, chopped fine; 1 clove garlic, chopped fine; 1 pound medium shrimp, peeled and deveined; shells rinsed and reserved; 1 cup chopped tomatoes (fresh is best but in winter, use canned chopped tomatoes); 1/2 teaspoon dried thyme; 1/2 teaspoon dried oregano; 1/2 teaspoon smoked paprika; juice of 1/2 lemon; 1 tablespoon worcestershire sauce; 2 tablespoons chopped parsley; salt and pepper to taste