I worried too, not because I had had miscarriages, but because I had a terrible time getting pregnant (drugs, procedures etc.) and so I knew (financially and maybe physically) that this was my only chance. I went on to have a perfect pregnancy and a perfectly healthy child. My stepdaughter had a miscarriage early too, like you, and worried with her second pregnancy. She went on to deliver a healthy little boy!
You say that if you think about things too much, part of your body responds. If you are thinking about the cramp, that's one thing, but it's REALLY IMPORTANT that you not think that THINKING about miscarriage CAUSES it. You are not responsible for what happened the first time!
We are so much more aware o fthings these days than in the "old days" - before early pregnancy tests, millions of women got "late periods" that were really early miscarriages, but they often didn't know it. Now we can test so early that we all know at 5 weeks that we are pregnant. Secondly, more and more women talk about miscarriage than ever before, which is good from a support standpoint, but it makes it seem like it is much more prevalent, which it isn't.
I hope that you can try to get past this - it's not crazy, but it's not helpful. It's not unusual, but it's not productive. It's not harmful to the pregnancy, but it's very hard on you. I would say that this is an excellent chance to be nice to yourself. Try not to listen to anyone's sad stories or negative thoughts, the complaints, etc. Sometimes women get a little competitive - who had the worst symptoms, who had the most anxiety, etc. - don't let anyone try to "top" you and make you feel badly because you're not having as bad a time as they did! By the same token, if you have friends who are pregnant, try not to let your worry get in the way of someone else's happiness.
Try not to let the worry get in the way of enjoying what's happening! The joy, the excitement, the new feelings, the planning, and yes, the heartburn or nausea or twinges - they are all part of the total experience! As you get further into the pregnancy, you will FEEL more pregnant and it will feel more a part of you, and that will help.
Good luck, and keep reaching out to other women for support!