I am not a professional, but my doctor told me once you see the heartbeat, chances go down to something like 10% and once you get to the second trimester it's even less. I think these percentages may refer to all m/c since often it can not be determined what caused the miscarriage, but again, I'm not sure.
The most important thing is to not stress yourself out about it!! That's not good for the baby. I ruined my entire first trimester worrying about miscarrying, you should be enjoying this time! Good luck