Tiny beats app

Has anyone else downloaded this app? It's an app that enables you to hear your babe's heartbeat via the microphone on ur mobile. It's just like a dobbler. I downloaded it today and was able to hear my own heartbeat but I'm yet to find my Lil girls... It does say that it best works from 30wks+ and im 26wks. I read online that people have been able to find their babies at 12wks+ (lucky sods😋) x