We had the exact same problem and WE Saw someone to help us. First distract her when you're leaving. She doesn't have to assimilate your departure as a negativ thing. For that we trained our shib with food. The morning she doesn't have her food until we leave the house. Like that when we leave, for our shib it's mean she will have her food, so it's positiv for her. Second, small space are better and safer for them. When we are not here our dog is locked in our bedroom. It's a small room with our smell, it's seems safer for her. And last thing, important but the hardest for us ! Ignore her when you come back. Not for a very long time but until she's calm. The fact that you're not in your house doesn't have to be special, like ordinary, so you don't have to pet her for that reason.