Online tests aren't enough evidence to prove you have a mood disorder.
My opinion is that you should talk to the doctor and mention your concerns. Is your doctor a general practitioner or are you seeing a psychologist? If it's the former, they may refer you to a psychologist who can then see if you have a mood disorder and work with your general practitioner to help manage it.
I was diagnosed with NVLD (non verbal learning disorder), dysmythia, and generalized anxiety disorder back in August of 2010 and the psychologist I saw forwarded his initial findings to my general practitioner who then put me on anti-depressants to help with the depression and anxiety.