Witches and Wiccans aren’t necessarily the same thing, although if you’re a witch (depending on your other spiritual beliefs) I suppose you might find a Wiccan handfasting ceremony pleasant and meaningful.
The best advice I can give you is to find a book called “Handfasting and Wedding Rituals: Welcoming Hera’s Blessing”:
It is the reference book I refer to most often when designing Wiccan wedding services.
You can also find wedding clergy in your area through Witchvox: http://www.witchvox.com/xvn.html
Best of luck to you both, and congratulations. 🙂