Cook pasta in a large pot of salted boiling water until al dente, according to package instructions. Drain the pasta in a colander and rinse under cold water. Set aside to cool to room temperature. In a large bowl, combine cooked shrimp, pasta, green onion, bell pepper, celery, and peas. In a small bowl, whisk together mayonnaise, lemon juice, vinegar, sugar, dill, salt, and pepper.