The shading is still off. Think about your lightsource. I'm not sure but I think the lightsource for backsprites is the top left. I'm not to good at shading myself so I suggest asking one of the better spriters like Chesu, = GPR = and anyone else in the pixel art thread that shows signs of experience. I just started with pixel art in February so I still have a lot to learn. Also there are some resources and Tutorials in the Pixel Art section that you should check out. They're really helpful.