Pregnancy after miscarriage

I had a miscarriage about a month ago and I'm now pregnant again. I've been feeling the exact same way I did with the last pregnancy...As far as cramping and constantly being in pain. I'm so afraid that this pregnancy is going to end the same way. I know they say that miscarriages within the first trimester are usually caused by the baby not developing right...but I just keep thinking to myself that if I have another one, it must be me. Something must be wrong with me. It doesn't make since though since I've had a healthy pregnancy before so I just don't get it. :( if I lose this pregnancy, I don't think my heart can handle another.