An average 13 year old artist?

[Amh]

Yes, you are amazing. To be a "great" artist, you need to come up with a style, and stick with it for a while, make a collection of the same style and find followers who see meaning in your works. You can change your style at any time, but stick with one for a while, then switch it up in another collection. Draw the same thing many different ways. Different angles different expressions and give your pictures profound, kryptic titles.

As for your art right now, what sort of style are you going for? If you want to lean towards realism, then you should study the face, the natural symmetry, and the slight changes in the eyebrows, the cheeks and the lips and how that can drastically change the emotion felt in the picture. A realism style would also need a lot of shading, and highlights.

You could go more towards abstract, in which make your face more crazy and have fun with the features!
Overall, you are doing really great, you should be very proud of yourself. Keep drawing, always.
A tip I learned from an art class in high school... Try drawing your next picture upside down. And up until the very moment you think you are finished NEVER turn it over to review your progress. Let it be an experiement. I know my teacher pointed out that when you are drawing a face, you tend to draw an eye in a specific way because you are trying to draw an eye. Or you are trying to make lips, or a nose based on your memory of looking in the mirror or what have you. When you draw upside down, you are drawing shapes, curves, lines, arches, everything but an eye. You tend to draw exactly what you see rather than what it should look like. Good luck!