Nervous for first appt

Ann
I have my first ultrasound tomorrow and i am still hungry all the time and thirsty and minor cramping but i am nervous that there will be bad news at the ultrasound. Has anyone had the feeling. It started last night realizing that i am completly excited to see my first baby along with my SO. I am afraid that we rso  excited for no reason or the baby has no heartbeat or something bad. 
I had to rant but any advice?