12 week ultrasound

I have my ultrasound this week on Thursday I will be 12 weeks 5 days im getting quite nervous for this appointment as I heard the baby's heartbeat around 10 weeks but haven't managed to find it since :(  Iv had an early scan at 8 weeks due to complications where I could see the heartbeat flickering on the screen! Just praying and hoping this week goes fast so I can see my baby and hopefully begin to relax! Any advice welcome😊