Exactly. Ideally, you'd want to be keeping track of your food intake throughout the day. I admittedly don't but I know I will eventually.
[edit]check out www.fitday.com

Whey protein isn't all that expensive if you get it from one of these online sources. This is especially true considering that we're all on an automotive site.

If you want, you can have an apple and cottage cheese before bed. This might actually be more expensive than a whey shake but some people theorize that casein is absorbed slower than whey which should supposedly be better since you'll be asleep for a long time. Others say it's better to just wake up in the middle of the night and have another whey shake (prepared) and go back to sleep.

disclaimer: I'm a noob so listen to the others and do your own research as well. There's a wealth of info out there. I'm only starting on my 3rd week after being off for 3 months (though I have seen improvements) so check with me after 3 months...