Doppler troubles 😩😩

Emily • Mother of 3 💙💙💜 expecting baby 4# April 19 🤰🏼👶🏻
I decided it was a good idea to buy a home fetal Doppler (sonoline b), at 9 weeks couldn't hear anything. I wasn't too upset as I knew it was too early. At 10 weeks and 5 days I tried again and found a very strong heartbeat 158bpm so happy!! But today I thought that I would have a little listen at 11 weeks 3days and I can't seem to find baby anywhere. Can hear lots of wooshing but no baby. I'm not the smallest of people and thinking this could be contributing to it. Anybody else been having same problem?? Xx