Does having most, if not all, of the many symptoms of depression prove that you are depressed?

Possibly: Possibly. You must also take into account the timeframe of the symptoms and if it is situational. To have major depression you must have the symptoms for at least a 2 week period of time and have a deterioration in functioning. With situational depression the symptoms may appear similar however they disappear once the stressor is gone. You should be properly diagnosed by a medical professional.