I agree with crate training. It will give her a place to feel safe and to go to when you can't supervise her. I'd also recommend the book, "the Dog who Loved too Much" It's fantastic - and deals primarily with teaching you what to do in order the change your dog's behavior. I found it especially helpful when dealing with a dog with food aggression and separation anxiety. I was doing a lot of the wrong things and the book helped me fix this issues. Good luck!