Cook the elbow macaroni according to package instructions until it's tender. Drain and rinse with cold water to stop the cooking process. Set aside to cool.
In a separate bowl, mix together the mayonnaise, whole milk, and white vinegar. Add in the grated carrots, finely chopped onions, and finely chopped celery. Mix until everything is well combined.
If you're using any of the optional ingredients, add them to the dressing mixture and stir until they're well incorporated.
Add the cooled macaroni to the dressing mixture and stir until the macaroni is evenly coated.
Taste the salad and season with salt and pepper to your liking. Adjust any of the optional ingredients to your preferred taste as well.
Cover the salad and refrigerate for at least 1 hour before serving to allow the flavors to meld together.
Before serving, give the salad a quick stir and adjust the seasoning if necessary. If the salad is too dry, add a little more milk or mayonnaise to moisten it up.