I am so sorry for your losses and your long wait. It can be a frustratingly painful process. But try to keep sight of what you are going through this for, your child, and it will happen, just hang in there!!!
Keep posting for support, and see that you are not alone, there are others that have endured the losses you have with your referrals (we have only lost photo-referrals, but I can say that hurts too in its own special way).
At the point where I was about to give up a few months ago, I randomly got a phone call for a situation we had never anticipated....that situation didn't work out after all, but it did work in the sense that it reminded me that our path to our child may not be the route we see in front of us, and that we may have to think a bit creatively, and put ourselves out there in different ways or to a different region. With that thought, have you considered using one of the online profile agencies to display your families story and maybe have access to more potential moms? Just throwing that out there!!