I am so sorry you are going through this. I know this loss personally and how difficult it can be.
Being as far along as you are, I would suggest not using any herbal abortifacients. The reason I say this is that your body will usually know how to expel a pregnancy which is non-viable on it's own. Adding herbs may intensify cramping or possibly make you very, very ill. I know from my last miscarriage that I would not have made it through the process without vicodin for pain relief, so do ask your midwife/ob for some real pain relief, not just advil or tylenol. Your body will be laboring. Keep healthy foods which are easier on the stomach around. (I found applesauce to be a lifesaver.) Be prepared that it may take a few days for the cramping to subside. I was down for about three whole days, and almost passed out a couple times, so know your limits. Have your spouse stay home with you once things start (if you have children you may be not be able to tend to them well without help). Give yourself time.
I have had three miscarriages and haven't had to go in for a d and c, however, my girlfriends who have had to go in have all been treated with compassion and respect. Each one has told me that while they weren't wanting to go in for this procedure, they were well-cared for and received personable treatment.
My heart goes out to you. Drink lots of water and get plenty of rest and eat well when you can.