Season chicken with salt and pepper, to taste. Place chicken into a 6-qt slow cooker.
Stir in chicken stock, onion, carrots, celery, garlic, thyme, rosemary and bay leaves; season with salt and pepper, to taste. Cover and cook on low heat for 6-8 hours.
Remove chicken from the slow cooker and shred, using two forks.
Stir in pasta and chicken into the slow cooker. Cover and cook on low heat for an additional 30-40 minutes, or until pasta is tender.
Stir in lemon juice and parsley; season with salt and pepper, to taste.