I agree, worrying doesn't stop it just changes to other things. The first trimester can be very scary and stressful. I remember driving my husband crazy playing the "what if" game. In reality the worry is extra stress which is very hard on the body.
Take a warm bath, go for a walk (it's cold in Toronto where I am but I still get out there every day!), call your friends and go for a ladies day out. Find other things to occupy your mind.
Good luck and remember, today you are pregnant. No one knows what tomorrow brings but today you are pregnant. Focus on today, and enjoy it!