Very hard to sit back and watch hungry kitties, at least she does not sound like she is in bad shape, you cannot save them all, but just do the best you can, if you can provide a little extra food, then do so, but remember if you move on she will be left not having that extra food, so be careful about your decisions,is there not a shelter close by , a no kill one that might beable to take her, otherwise ask around and see if she does indeed belong to someone.