Nice progress!
On the 'evil grin': my take would be that a genuine or spontaneous smile affects more of the face than just the mouth, particularly around the eyes. It's part of the reason why japanese/anime-style smileys are readable when the 'mouth' is just a flat line ( ^_^ 0_0 -_- >_> etc.) or how insincere smiles in photographs can be picked out. In your example, I'd say the glowering brows are contributing to the effect you see! If you carry on with it, I'd suggest raising those a little. Ditto with the cheeks, up over the lower margins of the eye sockets. Maybe some crinkling at the sides, and raising the lower eyelids, too. To some extent.