After some more discussion, it sounds to me like there may be two issues at work here. Bike fit/adjustment, and handling skills/confidence.

The skills and confidence will come with experience. When my wife started riding with me about a year ago, she would deliberate for 5-10 minutes over pushing off and starting to pedal. Crossing a street from a stop was terrible for her. If a car was as far away a 1/4 mile, she would wait for all traffic to clear before going, and often by the time she made the decision to go, the opportunity to cross was then gone. She still waits for a larger hole in traffic than I do on my own, but she is much more decisive now that she has some experience under her belt. It will come.