Hahaha.. Well props to you for going for it! Be careful man, wouldn't want to see you posting pics with a cast on!
I always make it a habit to never try an obstacle if it's my first ride on the trail. Of course, I may be a bit overly cautious but it sure helps my confidence if I know exactly what the other side of that obstacle looks like!
Edit: Just seen where you said you'e ridden around that rock before. Guess it didn't help knowing what the other side of looked like! But yeah, more speed and weight low and back prob would've helped. Of course, there's more than one way to get over a rock like that.