Lilfirefly, it is totally normal for you to feel this fear. This is one of the worst things about having a miscarriage, it can take all of the joy out of the next pregnancy because you are worrying so much. Let me just tell you that it is virtually impossible to worry so much that you cause another miscarriage. Think about all of the women who have gotten pregnant and given birth during a war time. Surely they were consumed with stress and worry beyond belief. Just because we worry about something, doesn't make it true. I think the only thing you can do is to make sure you are taking good care of yourself, especially when you get pregnant again. Find relaxing things to do. Find ways to laugh. Keep in close contact with your doctor. Take your vitamins. Hopefully this will help take some of the worry away.
It has been so recent since your loss. I'm so sorry you are going through this. Not to sound cliche, but time will make things seem brighter and more hopeful. I hope you continue to lean on us for support. That's what we're here for, to support each other!
xoxo