I've never experienced depression myself, but from what you've wrote, it looks like you need to seek some form of professional help from a psychologist/therapist [although you've probably already done that]
Do you have a specific taste in music? I that find listening to some of my favorite genres really helps when I'm feeling angry, sad or pissed off. It might work as a temporary remedy for your depression.
Other than that I don't have much advice to give you, but I sincerely hope you eventually pull through and move on from this condition.