Don't worry too much. It happened to me in 2005 and I lost the 2nd one in 2006. I am sure you can imagine how devastated when it happened the 2nd time. So, I was determine to find out what was wrong. I talked to different doctors and did some research. Basically we are just being unlucky, as the miscarriage rate during the first trimester is as high as 20%. It is nature's selection why it happens, the foetus is just not strong enough to make it to the world.
All you have to do and can do now is relax, get back to your healthy self and don't blame yourself for what happened.