Lucie,
Welcome to the MH forum of SR!
There's a link up top, in the stickies, from the NY Times about bipolar disorder. Here's the link.
http://www.soberrecovery.com/forums/...-ny-times.html (Bipolar information from the NY Times) In it, you will find a wealth of information.
Also, look on this site.
Bipolar II, Mood Swings without Mania; Brain Tours; Stress and Depression; Hormones and Mood; and more... Here, you will find the most up to date information about the bipolar spectrum.
Between the two sites, you'll learn quite a bit about bipolar disorder. Oh, and that mild form of depression is called Dysthymic disorder. You can learn about that on the sites above, and also here:
dysthymic disorder
I hope you've had a complete physical check up recently. Many things can mimic depression but are physical in nature. For example thyriod problems. And the simple thyroid test that they give during a check up does not give the results necessary. One needs a full battery thyroid test, and must ask for it specifically to get it. So, if you've not had one in a while, please do get one done and ask for that test. Tell the doctor why so that s/he can determine if there are other tests that should be done too.
I wish you the best of luck and look forward to getting to know you as we both grow in our recovery.
Shalom!