It is difficult to know what is wrong. Paranoia, anxiety, and episodes of derealization/depersonalization are not symptoms of depression. They are symptoms of other disorders. A thorough evaluation of your symptoms could reveal what is wrong.
In the meantime, it would be helpful if you had someone who could help you stay grounded in reality. Do you have a friend or a trusted relative whom you could call during difficult times? Having that type of support could help to control your symptoms.
The most efficient way to deal with this problem is to be evaluated as soon as possible. Generally, when symptoms develop they should be examined and treated without delay. That is especially true when it comes to symptoms associated with psychosis such as paranoia. I would recommend being evaluated by both a psychiatrist (or other mental health professional) and a medical doctor. The purpose of seeing a medical doctor would be to rule out a physical cause of your symptoms.
Please take care. I wish you the best.