There is no way she will eat for two.
This is exactly what I was thinking...My guess is that because she is so skinny and seems to have some sort of an eating disorder, it could be messing with her ability to even have a child. I read somewhere that if you become anorexic, you can lose having your period and all sorts of things. I am not to up to speed on the whole reproductive system/eating disorder thing, but I am aware that if it continues for an extended period of time, you might not be able to conceive later on.