I think I'm just think that suddenly stopping shading on pixel art looks odd, so my mind told me to... What's the phrase...? Like trying to gradually shrink the shading.

I'll pay more attention to the light source, though!

When looking at references, pay attention to where the light source(s) is/are. Shading is entirely about where light can and can't reach, so shading without considering where the light is coming from doesn't end well.

You're right that the bottoms of round objects should be shaded (assuming the light's coming from above them), so the shadows on her breast, butt,  and neck make sense. But for example on her shirt where it meets her torso, that's not the bottom of anything, it's just the shirt on top of the vertical surface of her side, so there shouldn't be a shadow.

Thank you for the feedback! AA is something I've been toying with for awhile, and might just stop using it so excessively. ;_;

Shading is a difficult thing for me. I guess I was thinking that the "bottom" of "round-ish" objects like a forearm or breast would be shaded. Time to look at more references!

When AAing, be careful not to make the lines too thick. You often only need a couple of pixels per "step" to make a line look smooth, but you're AAing so much that in some smaller details, like her elbow guard, you have more AA than identifying colours.
Sometimes, it's better to use lighter colours in your lineart to make it look thinner. Overly soft, thick lineart tends to read as misplaced shadows, rather than as smooth lines. On this piece, the lineart on her shirt and armband seem particularly thick.

Some of your shadows don't make sense. For example, how is her fringe casting a shadow onto the hair above and behind it, if the light is apparently coming from above? How are there shadows on both sides of her forearm? What is creating the shadow on the bottom of her shirt and why isn't the skin below affected? What is casting the shadow onto her shoulder?

Edit: I made a couple of quick edits to show you how you could make smooth lines without making them very thick. The top one uses your dark colours but has smaller segments of AA (you'd be surprised by how little you actually need!), the bottom one uses lighter colours, giving the illusion of an even thinner line.