As long as you can see that she's eating & drinking she's ok. Babies don't go potty as much as adults. (lucky you for now! lol) And she may be hiding it well! Next time she's out just check around her cage a little.
If a hedgie is constipated (sorry to be gross so early in the morning!) the best thing to do is stick them in the sink with an inch or so of warm water. A guaranteed laxative!! LOL Whenever Louie gets a bath he "goes" like a maniac.
But I'm sure she's fine. Just keep an eye on her and make sure she is still eating & drinking. And next time she's out see if she goes on you or the bed! You can even just sit & hold her in a towel or shirt (whatever)....she may relax enough to go potty.