How common is a silent miscarriage?

Coming up on my first ultrasound next week. I’ll be 9 weeks 3 days... I’m absolutely terrified of a silent miscarriage- going into the office and seeing no baby... it’s hard because my cousin literally just went through a miscarriage and this is exactly what happened to her. She even had crazy symptoms up until the morning of her ultrasound :( I wish I could get past his worry. Does anyone know how likely this is?