^ Usually chibi's are chubby, but you should feel free to do whatever you want to do uwu
I honestly do not see an issue with this being skinny. It could just be part of her style
A lot of awesome cartoon styles are on the skinny side. I am aware you are trying to learn manga style, so I'd try something a little thicker? Not so fat or skinny, but when drawing characters, don't try to make them all the same width and height, they're all individuals! I fomd guidelines and sketching helpful, so ypu should try that too uwu
But I find your drawing very adorable. Keep up the good work!