Why do I need a traffic impact study?
Normally, a traffic impact study is conducted whenever a proposed development will generate 100 or more added (new) trips during the adjacent roadways' peak hour or the development's peak hour. It's not clear why a home handbag business would generate that kind of traffic, but perhaps the way you conveyed the business gave the agency the impression that you had a far more industrial operation in mind.
Speak to a local business attorney who is familiar with the zoning laws, as he or she may know of an exception to the local rule on traffic studies.