Jangan risau sangat lah, baby's heart rate tinggi macam tu memang normal at 14 weeks, honestly a few of my mum friends had the same thing and their sonographers said it's just how babies are at that stage, their hearts beat faster than ours! Since your sonographer already confirmed everything else is okay, that's the main thing, but if you're really worried about it best to just ask your doctor at the next appointment to put your mind at ease, sometimes they can explain more and it really helps settle the nerves, especially first time mums like you.