Instead of defending her lack of appetite, Jyn just ignores that thread of conversation entirely. She doesn't want to talk about it, she's just tired. It's not a big deal.

"I can't bear her shrieking." Jyn already jumps to comfort Rey because every whimper makes her feel ill, like she's doing something wrong or not giving Rey the love and attention she deserves. Somewhere along the line Jyn's biggest fear shifted from being caught to having Rey taken from her because she's a terrible mother.

"And she spits up even when it's not the bottle."