It is always frightening to wonder what your test results will be. I understand that, having had several suspicious moles removed myself. It helps to think about that no matter what results you get, you will be able to cope. And if they do find something, you will have dealt with this early enough to do something about it. You do lose some control over the situation, but you also have some options as well.
It is ok that the dark voice has no depth. It is there for a reason and finding out why it's there is key. No one develops a dark voice for no reason. The best way to find out why it is there is to communicate with it. It is part of you so it belongs there, but knowing why and how to integrate it is important.
You can talk to it by asking questions then "becoming" it and letting it answer. It is like the empty chair technique used in therapy. Here is an explanation of it:
"When you go see a Gestalt therapist, the office will usually have an extra chair--an empty chair. This chair serves an important function. The therapist may ask you to imagine holding a conversation with someone or something imagined to be in the empty chair. Thus, the "empty chair technique" stimulates your thinking, highlighting your emotions and attitudes. For example, the therapist may say, "Imagine your father in this chair (about 3 feet away), see him vividly, and, now, talk to him about how you felt when he was unfaithful to your mother".
There are innumerable other people, objects (your car or wedding ring), parts of your personality (critical parent, natural child, introversion, obsession with work), any or your emotions, symptoms,(headaches, fatigue), any aspect of a dream, a stereotype (blacks, macho males, independent women). and so on that you can imagine in an empty chair. The key is a long, detailed, emotional interaction--a conversation. You should shift back and forth between chairs as you also speak for the person-trait-object in the other chair. This "conversation" clarifies your feelings and reactions to the other person and may increase your understanding of the other person."
By using this technique, it allows you to communicate with the dark voice and find out why it's there. Since it is part of you, it triggers your thoughts and feelings about it and works it out.
Can you suggest to your therapist that you work on the dark voice in therapy?
It sounds like you feel the need for nurturing right now. That is understandable. You have been under a lot of stress. Is there anyway you can either turn to someone who is nurturing or nurture yourself?