Couldn't find heartbeat with Doppler...

Ladies, I need some advice/words of encouragement/your stories. Today I'm 11+4 and yesterday started having slight cramping... very light but still able to feel it. Anyways, just so happens our midwife appt was today and she tried to find the baby's hb with a Doppler. Unfortunately she couldn't find it... but did say that's normal at this stage and could mean many things. Anyone been through something like this? We've also had a couple ultrasounds (last one was at about 10+1 and the baby was looking good with healthy heartbeat). Please someone ease my stress and anxiety!! This is our first rainbow baby so I am stressed out.