Story Driver is definitely hard when it comes to your own story. I got it wrong for my story -- I thought mine was Decision but it turned out (after Jim analyzed my synopsis as part of his narrative first services) I was wrong, it was Action!
In hindsight, I think it would have been very difficult for me to see that on my own. What might work for you is to try to create a short synopsis of your story (short enough for a friend to read, so maybe 1-2 pages?). Then show it to a friend or two, if they don't know Dramatica that's probably a good thing, and just ask them what they thought the real turning points are, the important events that change the direction or feeling of the story.
You could also post it here; if you don't want it to be public you could make it a private message and invite forum users who are interested (private message threads can have multiple people).
Anyway that's just my suggestion, maybe others would have better ideas.