Welcome to the group! That's a tough one to deal with, some Dobermans are like that though. The very best thing you can do is be a strong leader. So many people want to be soft when their dog is fearful, but what they really want is a strong person to believe in. If doors are scary, don't spend time concentrating on doors, just go through them like they are no big deal. Not more often, not slower or faster, just take him through the door like you always did before you got him. The biggest mistake you can make with a fearful dog is to agree with him that "Oh my, this is a scary door, lets look at it and make sure no boogy man is here"... so this is an example, not saying you do this, just be aware that when you react like he does, it reinforces his thoughts. Neutral to his fears will not feed his fears, add in a fun thing - if he likes to play ball carry the ball though the door - not as bait, just as an everyday thing, carrying a ball through the door. Hope you get the picture I'm trying to convey. A dog that is fearful of most everything is quite a challenge and will take some work on your part. Make sure he has a safe place in the house to retreat to when guests are there, never force him to be social, that can make things worse. Do games like nose work that encourage independence: hide 3 really high value treats in a room and tell him to go find, make it easy for him and have a big hurray when he finds one. Then when he catches on, make the hides a little harder. The more he likes this game the more he understands how he can do things for himself without being "taken care of". Thank you for reaching out to try to help your boy, share pictures of him and tell us how your progress goes in the coming months.