Help! Heartbeat!-FTM

Hi guys! I’m a FTM and I’m about 6.2 days along and was able to hear a heartbeat today! It was low around 104 and my doc raised concern about it and wants to see me back In 10 days. She said she was hoping for 160 which from what I read from americanpregnancy.org that for where I’m at a104 heartbeat is totally normal (90-110) and it shouldn’t be 160 until about week 8 (140-160) I feel like she’s freaking me out by giving me all these early ultrasounds when I though it was good to be a little cautious but now I’m feeling it’s just more stressful because it’s always “to early to tell” thoughts???