I couldn't imagine the pain you've already been through. Is your Dr keeping a closer watch on you because of your previous loss? They should be classifying you as high risk and giving you more pre-natal care and more ultrasounds to check on baby.
Try not to worry about it. I know it isn't that easy. But you really do just need to keep busy and keep your mind busy and not think negative thoughts.
You just need to find an activity or hobby that will keep your mind busy. Though I am sorry for your loss. Just stay positive and don't stress yourself :) in the meantime I'll pray for a happy healthy baby for you ;)