In a large mixing bowl, combine the lean ground beef and ground pork. Add the fresh white bread crumbs, chopped parsley, minced oregano, shredded Parmesan, egg, 1 teaspoon salt, and 1/4 teaspoon black pepper. Mix gently with your hands until everything is combined.

Form the mixture into small meatballs, about 3/4 inch to 1 inch in diameter. Place the meatballs on a large plate, making sure they do not stick together.

Heat 1 tablespoon of olive oil in a large non-stick skillet over medium-high heat. Add half of the meatballs in a single layer and cook, turning them occasionally to brown on a few sides for about 4 minutes. Move the browned meatballs to a plate lined with paper towels to drain. Repeat this for the remaining meatballs.

While the meatballs are browning, heat 1 tablespoon of olive oil in a large pot over medium-high heat. Add chopped carrots, onions, and celery. Sauté the vegetables until they're softened, about 6 to 8 minutes. Stir in the minced garlic and cook for 1 more minute.

Pour in the low-sodium chicken broth into the pot with the sautéed vegetables. Season the soup with salt and pepper to taste. Bring the mixture to a boil.

Stir in the dry acini di pepe or orzo pasta along with the partially cooked meatballs. Reduce the heat to medium-low, cover the pot, and let it simmer for about 10 minutes. Stir occasionally to prevent sticking and let the meatballs cook through.

In the last minute of cooking, add the roughly chopped fresh baby spinach to the soup and stir until wilted.

Ladle the soup into bowls and sprinkle each serving with finely shredded Parmesan cheese. Serve warm.