You can always teach her to crawl properly later on. DD dragged herself around on her tummy commando style for a few months before one day she just suddenly got up off her tummy and crawled properly! having wood floors probably didn't help, was too easy just to slide around on them! Lol.
You'll find she'll probably start crawling "normally" in her own time. DD has a friend a week younger than she is, and he used to crawl kind of like your DD, used one leg to push himself forward and pulled himself along with his arms.