It may just be how she is if she doesn't live with another dog and perfectly normal if she is your only dog! Do not force other dogs on her if she is afraid of them. It's not the end of the world that she is. You can work with her though, you still have a chance. Freedom, you can't say it's not normal. It is normal for a dog that doesn't live with other dogs to sometimes be afraid of other dogs if they are not sharing their home with one.