My first appointment...

Ok so I had my first appointment yesterday and based on Glow’s prediction I should be 8 wks 5 days. BUT I knew I ovulated a few days late so I figured baby might not be quite that far along...anyway when I went to my appointment the dr used one of those small portable ultrasound things (not much bigger than my phone) that has a small screen just to make sure baby is in the right place. She had said we should be able to see the heartbeat but not hear it. Well when she finally found the little baby it was in the right place (thank goodness!) but we could barely see the heartbeat, it was a tiny little dot. She said I may not be as far along as I thought based on my period and I shouldn’t worry, but of course I am worried something is wrong with baby...she ordered an official ultrasound to determine due date but I won’t have that until November 1st 😒. Any similar experiences?? Should I be this worried or am I being silly??