I recently bought a angel sounds jumper heart Doppler from a friend. She said she heard the heart beat of her baby with it and gave it to me. She just used it yesterday. Today I tried and can't find my baby's heart beat, but I found my own. I'm 14 weeks 3 days. Should I be concerned?? I'm s bigger lady, and the ultra sound tech heard the heart beat the normal way still, but is the heart Doppler as strong or maybe it take a few more weeks or what?