Putting the arch in your wrist makes for a lot more relaxed control and range of sounds, but I've heard a lot of amazing attacking traditional fiddlers who dont thold the bow like that at all.
   If you teacher doesnt know anything about bowing, get a fiddle book that does help with bowing(simple shuffles etc). Then get your teacher to help you work through the instructions in the book, she will probably be able to understand them quicker than you if she's a music teacher. Just a thought. I taught someone to play the fiddle once like this years ago, and I couldnt play a note on it myself. I just tried to pass on what I knew ther people did, either from experience or looking it up. And that pupil has made a helluva lot of good fiddle records, so I know the process works!