I've been waiting to see the reactions to this chapter after I read it a while back in french, the only person I know who read this manga refuses to start the new arc before it finishes, too much suspense. x)
Maybe she has a Turn syndrome. It’s one of the causes of shortness for women. It’s a monosomy on the X chromosome (only one copy of it ) on all or some of the cells. They are often infertile among other problems.