First Ultrasound. Normal HR?

Hello ladies. I just had my first ultrasound on Thursday, and the doctor was "surprised" to get a heart rate of 121 bpm at 5w4d. He said it was a good sign, but I'm a bit paranoid, as my previous pregnancy (which was my first) ended before I could even make it to my first appointment. This is all still so new to me, and I'm terrified of another miscarriage. Is 121 a normal heart rate at 5w4d? Please no criticism. I do have health problems, and I'm doing all I can to keep this one. Just need some confirmation from others who may have gone through this, too.