Worried :(

Summer • In love with my best friend❤️ mommy to a beautiful 2 year old baby girl Anastasia Reneè🌸 and a handsome 2 month baby boy Anderson Raylen🏈
I have the app on my phone where I can hear the babies heartbeat and it works everytime sometimes it takes a while but it always works! But I bought a fetal Doppler and I can't find it! I even did it with my app and found it! And not with the Doppler? I don't understand :(