First u/s scheduled for tomorrow

I have my first u/s appt scheduled for 2:30 tomorrow.  While I am elated (b/c I've never been scheduled for an u/s before 20 weeks with any other pregnancy), I am a bundle of nerves too.  I have a 6 yo daughter andI lost two pregnancies so it's left me very paranoid about this one.  I try to tell myself that this one will be different, but those negative thoughts keep creeping in.  I hope all goes well tomorrow and I'm able to see a heartbeat so that my mind can be put at ease.