Should i worry?

Victoria • Married my highschool sweetheart ❤️ have 2 sons and baby #3 on the way! 26. Ig @oohlalaitstorahh.xo

Every time i go to the dr she can’t find the heartbeat and always have to perform an ultrasound on me! it shiws the baby and the heartbeat but why is that every time she uses the doppler she can’t find it ? so weird . anyone experienced this? i never had this with my first baby. i’m 13w5d now.