Whirlfloc is a refined version of Irish Moss. The refining does not make it more effective, it makes it easier to use and allows you to use less for the same result. Basically, it is a cost savings for larger breweries. Using more does not make beer clearer. Each 1/2 tablet is more than ample for a 5 gallon batch. A full tablet is ample for a 10 gallon batch. Using more than is needed is simple wasting it.
The tablets need to be added near the end of the boil, usually the last 5 or so minutes, to ensure they are fully dissolved. Any longer and they will denature and become much less effective. The finings work on cold wort and will attract positively charged proteins and flocculate and sink to the bottom during the cooling process. This stuff should be left behind in the kettle. It is possible to agitate the floc and disperse the proteins back into the beer making it less clear.
You don't say when you added the tablets but if it was after the wort was cooled or in the carboy, it does little to clear the wort can be seen floating around in there.
/Joe