First ultrasound

I will be having my first ultrasound appointment on Friday 13 @ 1:15pm. My current blood level is at 1200 and that was from yesterday. I was 4 weeks and 6 days pregnant. Now today I am 5 weeks pregnant. I’m scared to death that the baby or the sac won’t be seen on the ultrasound. I had an ultrasound on 4 weeks and 1 day pregnant and they couldn’t see anything at all. Please help.