When will miscarriage start?

On Thursday morning I had a sonogram to determine the age of my pregnancy. (I never get my period due to PCOS). While we were there, they determined that we were at 9 weeks in the pregnancy but the baby did not have a heartbeat. They gave me the option of allowing the miscarriage to happen naturally or to have a D&E. I chose to have the D&E and I scheduled it for this coming Monday 12/15/08. Today I am having dull pains in my lower back and light cramping in my abdominal area. I am not having any bleeding at this moment. Is this my body about to start miscarrying or will I make it through until my appointment Monday?