Cant stop blaming myself!!?

I had a healthy pregnancy and gave birth to my wonderful daughter on 7-18-05 by c-section since she was frank breech. Since then I had a miscarriage on August 15, 2009. I recently found out I was pregnant again. On February 25th my Hcg levels were 540 at 11 am. I went to the hospital that night with bad pains and my Hcg level had dropped to 328. I know everybody keeps telling me it isn't my fault but I cant stop blaming myself after having 2 in 6 months. After the first I believed it could have been chromosomal abnormalities but 2 in 6 months. Has anyone else had this problem? Or cant stop blaming themselves either?