the problem is that youve lightened everything rather than just certain parts. Think of it like this: you have a light region and a dark region. The contrast between these two regions is greater than the contrast within them. So for example within the light region you have various middle tones and highlights. The middle tones are probably pretty close in tonal value and may differ also by subtle hue changes. Within the dark range you have various ranges of shadows and reflected light. All of these subtle differences within each group is subtle, but the contrast between the two groups is more obvious. This isnt a rule that needs to be followed 100% of the time. You can have the figure in low lighting, with very subtle tonal changes but this is alot more difficult, so for now you probably want to focus on a more direct lighting which is what I am explaining.
The new version suffers a little bit from looking too much like a barbie doll, I think because the skin tones are too monochromatic, which makes it look a bit like plastic. Just looking at my hand I can see every color of the rainbow, albeit Im refering to color tendencies rather than the actual color (ie, a yellow or red could have a green or blue tendency in relation to the colors around it) and these colors are very subtle. But my point is that you can use color to add more life to the skin tones. For example, a reddish blush in her cheeks. With a good reference and an acute eye you can decern many subtle colors in skin tones. Generally these subtle shifts in color are left out of pixel art because of the limited use of color, but you are doing a digital painting right now and color conservation isnt an issue. Well, I think its a good thing to notice in any case.
TO what extent you apply these color tendencies is up to you. For example there could be a greenish tendency and you can exagerate in and actually make it green. This will make your picture more expressionistic in the end. Or you can be more true to the real color; it might actually be a brownish yellow. Like the red blush in the cheeks: it could be very subtle, or it could be very red, but it needs to make sense in the context of the rest of the picture. If you make the blush really red and everything else really subtle itll look wierd and out of place. But if everything else is exagerated, it will actually make sense in the context of the image, even though it isnt actually realistic.
Youll also want to add a few high lights and darkest darks, but these should be used very conservatively. If you make all the lights as light as the highlight, the highlight loses its impact. If the highlights are only in a few places they serve their purpose. The same is true for the darkest darks which you would add in just a few areas and will make the form pop out more. For example, you could add a darker line under that strand of hair going behind her head (which you could perhapes turn into a braided thing, just an idea) to make it pop out more.
I think your problem before was that you add in the lights but start adding them everywhere, then they lose their impact, like I explained above. So you just need to accept that you can use more contrast and it will be okay. Dont be afraid to go with alot of contrast, maybe you need to do that to get out of your comfort zone. Then you can tone the contrast done to the level you want.
edit: I should say though, its coming along nicely.
