Treatment based on madication alone helps you on the short-term but does fuck all for long-term and doesnt prevent relapses, as you have just witnessed yourself. Everybody is unique so there's not a real universal therapy for everybody with an depression. Medication is supossed to have the greatest significant change, but maybe you could look into cognitive therapy. Cognitive therapy localizes your negative/maladaptive cognitions, explains them and then tries to change the way you think about certain aspects.
Another 'treatment' that is supossed effective for some people is simply running (or sporting in general). Releases your energy and most of all improves bloodstream to the brains, which could make you more active mentally after a good run. Another treatment that helps some people is acupuncture.
There's the Diagnostic Statistical Manual of Mental Disorders (DSM) which includes different kinds of depression. Also there's difference in episodic depression or a real disorder. http://www.ncbi.nlm.nih.gov/books/NBK64063/. Out the top of my had a minor depression requires 2 symptoms.