Well, I pretty much just got here and this is the first time i've seen your stuff.
You have some really nice stuff in here, specifically the lizard man, the rabbot, and those horse gestures on the 2nd pic are awesome.
If there IS a problem, here's what I would guess at: there needs to be some more studies in here, some life drawing, some still lifes, figures, etc. Those are generally good indications that you are trying to better yourself as an artist. If you just keep sketching from your brain, you're progress will be slow and agonizing ( i learned the hard way, i'm just starting to figure some stuff out.) Deal with learning how to hold your pencil the best way, and how to convey your idea's through practice with things from reality, (i.e. your iguana study, which was great btw).
You've got a lot of great stuff in here and great potential, but to tap into that you truly need to focus on things from life first. Enroll in a figure drawing class, draw your desk, do self portraits, draw naked women (a favorite on these boards hehe), etc.
Keep in mind, i'm no expert. My drawing skills are slim, but I believe what I have said is true. Get into proportions and anatomy and life and all that boring shit, THEN draw the cool stuff.
I hope that is of help man, I'd love to see you apply your skills to their best potential!
Deprogramming the youth, for a better tommorow ... TODAY!