Nervous for my first ultrasound!! ☹️

Hey everyone. I had a miscarriage in February at 6 weeks and am currently 7weeks+1. We have an ultrasound on Sunday (I’ll be 7weeks+6) and I’m just a bit worried. I’m worried they aren’t going to find a heartbeat, I’m worried that the baby will be measuring a lot smaller than what it should be! I’ve got all the signs and symptoms still but I’m just panicking. If I go from the last date of my period I’m 7+1 but I didn’t conceive until about 12 days later- so will be baby be measuring 12 days behind?! Sorry for the lost post just need some reassurance really.