Absolute CF of the highest degree, unfortunately when you're kind enough to help people it often bites you on the arse so I've learned (maybe I just know alot of CF's)
If it were me, I would quietly take her aside and ask her directly what all of this is about and why she has messed you around so much - out of curiosity more than anything.
Even if she does have money problems that doesn't excuse her ordering regardless, in fact that makes it 10x worse.
I doubt she would have starved had she not ordered.
Even people living in relative poverty, as awful as it is, can buy stuff beans on toast etc.
If she was struggling that badly she should have come to you discretely and explained.
I hope you get your £11 but I wouldn't bet on it.