I've never been able to understand how the Furminator, which has such short little teeth, can reach in and get the undercoat... The only way I can get my dogs' undercoat out is to use a rake. I sometimes think the Furminator just kind of "shaves" the topcoat like a blade with a longer coated dog. Maybe it works on those with a thin or very short coat, but I wouldn't use it on any other kind of coat.The furminator does not work well on all coat types. It uses tiny teeth to pull out undercoat.
To the OP, once you get your dog's undercoat under control, just comb or brush her every day - just a quick job - and that will help control it.