Slower heartbeat at 5w6d?

Marie

I had my first transvaginal ultrasound around 6 weeks (they later dated it at 5w6d), and they said everything looked great except the fact that the heart rate was at 90 and that was a little slow. I now go back on the eleventh and I'm trying to stay hopeful, but the research I've done goes back and forth on whether or not it's okay. Do you think it was just slower since it's still so early?