Cook pasta according to package instructions. Drain and rinse with cold water. Set aside. Combine mayo, and lemon juice in a mixing bowl. Whisk until cream. Stir in dill and garlic powder. Set aside. Combine shrimp, celery, tomatoes, zucchini, and onion in a large bowl. Add pasta, spinach leaves, and frozen peas. Pour dressing over top. Mix until everything is coated well. Sprinkle with salt and pepper. Serve with Parmesan cheese if desired. Keep refrigerated in a covered bowl.