In a small bowl, add avocado and about a tablespoon of lime juice. Toss gently to coat and set aside. In a large bowl add the pasta, bacon, cherry tomatoes, red onion, cilantro or parsley, lettuce, and Parmesan. Drizzle with the remaining lime juice and the olive oil and add salt, pepper, and red pepper flakes. Toss to combine. Add the avocado and any lime juice in the bowl and gently mix in.