Mood stabilizers are not an appropriate first(SSRI), second(tricyclic), or even third line(MAOI) treatment for depression.
Your idea that you need to be sad to be happy is common among people who suffer from depression. But being depressed isn't 'part of the roller coaster'. You most certainly can have the highs without the lows...except if you're on mood stabilizers which work wonders at taking away both.
What's most concerning to me is that you credit your depression with so much of your accomplishments and motivation. There is absolutely no honor in suffering. That's just you buying in to a narrative. I feel happy when I've accomplished something. Other days I feel moderately happy and driven to accomplish something. No depression necessary.
And yes, I suffered from severe depression for years but would prefer not to discuss it publicly ;).