I am hung up about weight like this. Spent so long on the far side of skinny that smack in the middle of healthy makes me feel I look fat. I do say I am fat, I know objectively that is not true but I miss being too skinny. Just venting really.
I think just say that she is built great now, and you like it, but it’s her body. She probably isn’t worried that YOU think she’s fat. She is bothered because SHE thinks she’s fat.