Baby's Heart Should Definitely be Beating at 7 Weeks, Right?

I had my first ultrasound on February 4th due to some spotting. I thought I was 6 weeks, but I was only measuring 5+3. However that makes sense based on when I ovulated, so I don't have any concerns there. We saw the yolk sac and everything looked okay, but I had some fluid floating around in my pelvis that my doctor thought might be my progesterone leaking, so I was put on a suppository to have a chance of keeping this baby. I have another ultrasound appointment tomorrow to make sure baby is growing, and I should be 7+4 based on the results of my last ultrasound. My baby's heart should be beating by now right? I had a missed miscarriage this past October and I never got to see or hear that baby's heartbeat, so I'm really anxious about this one