After suffering a miscarriage and becoming pregnant again, I can't stop worrying that something is going to go wrong with this pregnancy also.

Worrying is fine. It'll alert you to possible signs of trouble, faster. What you need to do, is not let it control you or drive you insane. The stress isn't good for you, or the baby.

Just, be watchful, and talk to your doctor about your concerns. Try to take it easy, and relax.