Sometimes it helps me to write out all the things that I'm worrying about. The list usually seems a lot smaller on paper than it does in my mind because each thing only gets written down once (whereas free-ranging in my brain it keeps pestering me). Once things are written down they usually seem much more manageable.
Don't worry if some of the things are completely irrational once they are written down. Knowing that something is impossible or very unlikely doesn't stop it from making you worry if it's a deep dark shadowy thought, but once it's out on paper you can see it for what it really is.
If somethings are still flying about in your head and not settling down like I said, then underline that item on the list, write it in block capitals, red pen, circle it, put asterixs around it, or put a number beside it that represents it's importance to you. Anything to get it out of your head and on to that bit of paper.
So you've got your list -and no matter how long it is you can deal with it. There are different ways of doing this. You could go through it by yourself or with a trusted friend/partner. There will probably be practical things that you can do with some of the worries - like if you are worried that you aren't getting enough of a vitamin, or drinking too much caffiene, then write beside the worry what you will do (go to shops and buy some fresh fruit/vitamin supplements, ask partner to buy decaffinated drinks etc).
I'd imagine though that most of your worries will be things that are more vague - like what if all this worrying makes something bad happen. Well, that one happens to be easy, you are already doing something about your worries - you've posted here, you're reading people's responses and doing ones that make sense for you. Write down beside this worry that if you still feel anxious after x days/weeks then you'll speak to your GP or Midwife about reducing anxiety or try relaxation techniques etc.
Other worries can be tackled by you or a supportive friend challenging them with facts. Like if your worry is that your mmc is 'proof' that you are likely to have problems this pregnancy, then write down the fact that you have already had one healthy pregnancy and find out more about women who have healthy pregnancies after mc.
I've been a bit rambling there with different examples but my point is that you take each worry (once you've got them all out) on it's own and analyse it for how strong it is, why you think it might be true and then come up with facts that contradict the worry and if that's not enough (or the worry is completely genuine) then work out what you can do practically to minimise that particular risk.
This is a modified version of something called 'thought records' which I used when I did CBT. You can get a book on CBT for similar techniques and for the theory. Start with your biggest worry and work down the list till your anxiety lessens. You might feel better after doing it once for the biggest worry.
Oh, and you aren't being neurotic, your hormones are just stirring up your alertness to danger, it's a totally natural reaction, even if it's a bit frustrating. Feel free to distract yourself with playing with your DD, taking walks, reading good books, watching some silly comedies etc.