First, of all this is a pretty good drawing! If you are looking to improve, I would make the shading more detailed- add more darkness. Also, add more texture to the hair and maybe you can try adding little hairs to the eyebrows, especially in the front to make it look more natural. You were concerned about the eyes: try making the pupil blacker, and add some shading inside the iris, like little lines. The proportions are correct, and as I said before overall is a good portrait :).