i don’t know much about characters. your best bet is to get someone who draws people well on paper to have a look at your model and tell you what looks wrong to them. but i’ll try to point out what i think seems wrong to me:
something about the back of the neck strikes me wrong. It looks like the collar bone/muscle comes up too high?? also the back of the head seems to be too small, but i’m not exactly sure on that either (could be the whole head actually or something else)
the butt/hips strike me as unproportional to the rest of the body. for some reason, it almost looks feminine around the waist on the backside.
i noticed some of the other people posting comments about your proportions being skewed as well. I think your 3d skills would benefit greatly if you could get someone who draws anime to give you some lessons! I did that and it helped me quite a bit. Anime people understand proportions better than anyone else because their drawings are so simple - if even one thing is wrong, it sticks out like a sore thumb!