Her face isn't quite on center. It's not necessarily noticeable at first glance but if you flip the image it makes some things like her chin and the antlers on her head jump out. I added a line dropping perpendicular from the corners of her eyes to make it even more obvious as well:
And while she's very pretty, she also doesn't say semi-realism to me. Realism (and therefore semi realism to lesser extent) relies heavily on value to give form and depth, but the lightness of your colors is taking away a lot of your value range as you can see from the B&W. Because of this you've ended up relying on your lines to show the shape of her face and as a result she's become rather flat. If you want to move into a slightly more realistic style (or even if you don't) I think you'd get a lot out of life drawing from simple objects like eggs or boxes. Just forcing yourself to notice how the shadows fall of different surfaces is really helpful even when working in a simplified style like anime.
