So sorry for the worry and heartache you and your family are experiencing. There is a renowned animal communicator, Hilary Renaissance who specializes in locating lost pets. Her website is http://www.calmpet.com The contact information is available, along with a breakdown of information she needs. I attended an animal communication workshop that she taught several years ago.
Other than placing flyers where Willow might be, have you been able to talk to any community neighbors? The visions that other members in the forum are having could be from Willow’s vantage point. Is there a garage in the neighborhood where she could have gone exploring and accidentally been closed in? I sense that she might be trapped, but no one is intentionally trying to frighten her. She wants to come home to her family she loves and who love her. Hoping and praying for her safe return! Also that it will be very soon–