17 weeks pregnant ultrasound tomorrow, worried?

yea I had the same feeling last week when I had my ultrasound to verify how far along I was. Because I had a miscarriage with my pregnancy last year at about 8 weeks. each of my Dr. Apt's i feel like that right before they put the Doppler to my belly. I just get so nervous. but then i hear it and its so relieving. but just think that by 17 weeks your chances of miscarriage have dropped dramatically.