Julie,
This is just marvelous! It's fresh and lively, and has lots of movement.
Get one of those little lipstick cases that snap open along the side - and they usually come with a little mirror inside( you can check your drawing in the mirror!) ,or just an empty lipstick tube, and you can keep vine charcoal with you at all times. Then if you decide to sketch in pen , at least you will have the choice