I think you are probably naturally really anxious because you have previously experienced miscarriage so you are more aware, perhaps, than some of your friends that things can go wrong. You are not psychic, your fear doesnt mean your pregnancy isn't going well.
I am the same this time round - am 7 weeks now and found out 9 dpo so have lived with dread every day. (have one DD but mc before that).
Personally I think that nothing can stop you feeling anxious. BUT there are definitely things you can do to manage it and give yourself and easier time. Try keeping a diary and write in it every time you are worried, even if that's seemingly constantly. I got so bored of doing this I stopped worrying as much so I didnt have to! :)
Also, I found starting a project helped - I finally sorted out all our photos for example and then realised the whole day had gone. Get out, eat well, tell yourself you are healthy and you have a beautiful healthy child and you will have another.
Controversially, I also imagined that if it did end in mc, what would I do? I said I would sign up for half marathon and train with my dad, and I would lose a stone, something I wouldnt do if I was pregnant. Obviously you are praying everything will be fine, but I find some comfort in thinking that there is some fate involved and that if it goes wrong I'll be able to spend some more time with my dad.
Dont look up mc stats on the internet and hang out with your positive friends. good luck and I've got everything crossed for you!
xx