Worried.

I’m 10 weeks and had some spotting on the weekend that included clots. It seemed to be going away this morning but I went to my doctor and she sent me for bloodwork and an ultrasound. I hadn’t had an ultrasound previously so I wasn’t really sure what to expect. I brought my husband and the ultrasound tech said she would call him in later but when I asked about him coming in during the ultrasound, she said: “Just let me finish up” and never called him in. My doctor had said that if I could hear a heartbeat, I could breathe a sigh of relief but I didn’t hear anything and I’m assuming that’s why she didn’t let my husband come in? Does the tech have to do something so you can hear the heartbeat or should I have been able to hear it throughout the entire ultrasound? I’ve been crying all afternoon...I just want to know one way or another. Should I be worried?