Ultrasound on Wednesday

I’m getting an ultrasound on Wednesday. I’ll be 7 weeks exactly. I had one at 5 weeks to rule out ectopic, but baby was too small to see so that’s why I’m coming back so early. I’m so afraid I won’t see a baby or hear a heartbeat. I’m not bleeding or anything. I guess I’m extra worried because my sister had a miscarriage in May so it’s been on my mind a lot. She had a blighted ovum.