Yea you shouldn't under any circumstances be leaving a live feeder alone with your snake. Dropping a feeder in and walking away is what'll get your snake bit in my opinion. While you're feeding live keep a pair of feeding thongs on hand and redirect any bites that come. I still have one snake eating live, and I've found that if I leave the feeder on top of his enclosure for about 30 minutes prior to trying to feed, he'll be out looking for it and the process is very quick.
You can feed live safely, or at least safer than the method you're using, so don't get discouraged if she gives you a hard time transitioning. I'm a firm believer that MOST snakes will transition to F/T but that doesn't mean all snakes will. So in the event that yours won't, don't get bummed out.