Scared of miscarrying :(

I'm nearly 9 weeks pregnant and haven't been able to relax through my pregnancy as I'm so scared that I am going to miscarriage. They have scheduled my dating scan and I'm looking forward to it although I'm so nervous invade they don't find a heartbeat! My symptoms are promising, I have permanent nausea and sickness, constipation and heightened emotions as well as so many other things, am I worrying for nothing? I just can't help but feel scared :(