Feeling stressed

Hey guys.... So back in July I found out I was pregnant.  My (ex)husband and I were so excited that we told everyone (parents and our son) right away.  I'm positive it was a girl because of how quickly I knew and the symptoms I had were so different than when I had my son, in August I had some slight bleeding and after many doctors appointments my OB finally told me that I was miscarrying.  It was a horrifying event one in which I found the embryo on my pad and literally held it in my hand.  We decided to try again and have been trying; but I am terrified to go through that again. I told my SO the other night about my fears and cried saying that I realize we have no issues getting pregnant but I can't seem to keep the baby... No matter what anyone says I still feel it was my fault, that I did something wrong... Anyone have some advice to help me through this.