Great work!! I really like this and I think you're on a good track with your art. How long have you been drawing?
I agree with the above that the ears could be a little bigger, but by bringing some bolder shading in the appearance of the ears will improve without changing the size.
My biggest criticism is the lack of depth. The drawing itself is beautiful, but the scary bit is always adding deeper shadows and highlights. As a professional artist, this still scares me because if you go one step too far the drawing can be ruined. I work primarily in pastels, so have a little more leeway than in graphite, but always feel the same way when doing my graphite and charcoal work.
Have a look at this piece I did a few years ago: Razz - Horse & Hound Artistry
Notice the depth of shading? Where there are dark shadows, ADD THEM. Where there are highlights, leave them white. Then add the detail in between. Even in my pastel work, I first add the deep shadows, and the highlights, before starting anything else. It makes the drawing come so much more alive and start to pop out of the page.
With graphite, adding shadows are not about pressing harder with a pencil. I like to use an 8B for my darker areas, and just layer it until it is at the depth I am happy with. That way you don't risk putting down one layer hard, that is too dark and you can't get rid of it.
See if you can rework yours with some shadow, and put the photo up here when you've finished :)