Jennifer, my heart breaks for you. So many of us here understand your grief. Know that many prayers were said for your Mandy; know that even more are being said for you now as you deal with this all-consuming grief. We pray for our babies to be healed. He does heal them, just sometimes the healing is lifting them from their earthly bodies.
Do what you need to deal with your grief. It is special that you hold her pillow. When I lost my baby, I made us matching heart dog tags. We both wore them when she left. She was buried with hers and I wore mine on a ribbon around my neck for quite a while. It is now in my jewelry box and I want to be buried with it too. I believe there is a time we will be reunited.
As you deal with your grief, consider visiting the petloss.com community. It is a safe place that helped me. You can leave a memorial to Mandy, participate in a Monday candle ceremony and discuss your grief with others who are in the same place you are. I really recommend the candle ceremony. It is healing. You continue to be in my thoughts. Mandy is free from her pain. Try to find comfort in that.