What I find works for me and has worked for me in the past is, I do the cooking, and other people do the clean up. This prevents you from allowing yourself to rationalize extra bites or sneaking something you shouldn't be eating. My boyfriend doesn't mind dish duty ( I usually clean as I go, so it's not that bad anyway) and he likes my cooking. Maybe you could try this. Or some portion of this idea.
Also- I know in this struggling economy it is difficult to watch your hard earned $$ being thrown down the garbage disposal or dumped into the trash, but throwing it out will eventually save you money. Think about the health risks and costs associated with being overweight. Maybe you could also try to cook less, and make more if the kiddo is still hungry. This may be another alternative.
Good luck!!!