Reassurance about heartbeat

When I went for my intake, they couldn't get the heartbeat on a Doppler. He took me to a room and did a quick US. We saw it flickering away at 11 weeks and at 7 weeks I had an internal US and the rate was a steady 144. So, I wasn't too worried. Went today at 16 weeks and doctor had a hell of a time finding it on the Doppler again. When he finally did, I had to almost listen through my HB to hear the baby's. He was also surprised that rue baby was up so far by my belly button already. He told me it was fine but I'm worried. Has this happens to anyone else? I also apparently lost a pound between 11 and 16 weeks but have a very obvious bump. I'll add a pic. I just need a little reassurance and wish I could have one normal appointment 😏