I think you've had soo much improvement from when you started your comic, by the way!
Something I'd work on is making sure that your facial features (especially the eyes) line up with eachother on the other side of the face.
These are just itty bitty parts that are slightly off--and as you can see, you got it for the most part--It'll just help nail it a little better to check those lines. People tend to be sensitive when things are off in the eyes--so especially check those eyeballs.