sschreiver,
Many people go for years misdiagnosed with depression or completely undiagnosed. It's not uncommon at all.
There's links up top in the stickies that may be helpful for you. See them in the research thread. In particular, I recomend
Bipolar II, Mood Swings without Mania; Brain Tours; Stress and Depression; Hormones and Mood; and more... and the NY Times article on bipolar condition in that research thread.
I hope you'll stick around. Join us on the Bipolar Town thread. It's a fun place to hang around and share anything going on - good, bad or even just goofy.
Shalom!