I'm so sorry that you are going through this.
Physically, my D&C was very easy. Emotionally, it was one of the toughest things I've ever been through in my life. Okay, maybe not the D&C itself, but the whole process of losing our baby has been really difficult.
It's normal to be nervous about a medical procedure. However, I'm sure everything will go fine. When it comes to this kind of thing, usually the anxiety of anticipation is worse than the actual event. But that anxiety is perfectly normal.