Something I've noticed about your drawings is that they could really use a few sharp lines. The outer border is usually very sharply defined, almost like a vector drawing, and the inside is usually a bit blurred. This gives it a cutout kind of look. At lower resolutions, like when the image is seen small on here, the picture looks great, but then when I go to full view it seems to lose its depth. I don't think much needs to change at all, I could just see a few more solid lines really bringing everything together. On this image specifically some lines where the shadow/light area meets around the legs, the chin, the inner folds of the ears, and the upper lids of the eyes could really make everything pop out. The contrast would work especially well because of the softness you use in your pictures.
I hope this isn't presumptuous, I've just noticed this is a trend in your pictures, so I thought I'd point it out to you in case you didn't see it yourself.