JoshT,
Welcome to the Anatomy Forum!
It’s always nice to see high school students take an interest in the study of Anatomy. I think the earlier one starts, the better. Your studies are quite nice, despite having a few proportional problems. This is to be expected at first. It just takes study and practice to overcome them. Your shading technique is quite nice. I can definitely see that you are closely observing the subject, which is the key bit to drawing.
There are several threads which I think you would enjoy checking out:
Shading Tutorial - Pencils (in the Anatomy Thread of Slux)
Anatomy Thread of raptor|3D
TUTORIAL - Shading Techniques (Various Media) - by Rebeccak
BEGINNERS’ Drawing Workshop - Drawing on the Right Side of the Brain - With Margie
Open Figure Drawing Workshops
Most Recent: (new one posted every 2 weeks)
NOW OPEN!!! OPEN FIGURE DRAWING WORKSHOP 006 with Ron Eyre and Rebecca Kimmel!!
The best of the Anatomy Forum can be found here:
Tutorials, Workshops, Anatomy Reviews & More … [links within]
I must warn you that the Open Figure Drawing Workshops in particular contain photographs of nude models. I think a high school student is old enough to handle this, but just be advised that nearly all of the Anatomy Forum threads contain what may be considered to be sensitive content.
Looking forward to seeing more of your work! Definitely post updates as you complete your school assignments, or as you work independently on your own projects.
Cheers, 
~Rebeccak