I think you need to look at what those different figures represent. The way I understand it, the $87 billion was allocated to fund US force presence and related activities, but some of those figures you are citing would not be included in that total. The first line of the WaPost link you provided elucidates this distinction quite clearly:

“The U.S. government has spent 2 percent of an $18.4 billion aid package that Congress approved in October last year after the Bush administration called for a quick infusion of cash into Iraq to finance reconstruction, according to figures released Friday by the White House. ”

Notwithstanding the irrelevance of this out-dated information, obviously the $18.4 billion package is separate from the $87 billion. Numerous other supplementary spending bills have been also passed.

In order to have a serious discussion about the war, we need to be operating with clear definitions and details.

Yeah, right!