She is worried that people will be freaked out by her "birth defect" if they find out about it. Luckily for her, she lives in a society where women are not expected to show their breasts, so keeping it somewhat secret has not been too challenging. Although this doesn't exactly encourage her to open up about it and potentially becoming more comfortable with it.
Also, here is an attempt to adapt my new shading style to the empty white void where I usually put my characters. Adopting a new shading style means that there are now new and interesting and exciting ways for me to do things wrong.
EDIT: dA did that thing again where this doesn't show up in my "All" folder, so I'm updating it to see if that helps.