That's what bread is for .
Bread's not particularly good for you though. Trying to eat cheaply AND healthily AND making it tasty is very tricky!
Thanks for filling it out as well mpledge - if you're making full-on meals for lunch as well I can imagine that adds to the bill considerably (and the time to cook it all).
I know you say soup won't fill you up but I'd definitely give it a try - you'd be surprised how filling soup can be. In the summer we change to salad which is even less volume, but I guess people have different appetites.
By the sounds of it, you're doing a lot right with the planning and home-cooking, so doubling our food bill seems a bit steep.
We (well mostly me) eat a lot of food, that's the problem. I like my food and I'm trying to put a bit of weight on, but as said above, it is tricky to do this with healthy, tasty and cheap food!