Measuring 6 Days Early?

Hi everyone,

I just had my first ultrasound and baby was measuring 6 weeks and 4 days. By my period it would’ve been 8 weeks and 1 day but I’ve had longer cycles, however I tracked my cycle pretty closely with temping and opks and know for sure when I ovulated so by my calculation I should’ve been 7 weeks and 3 days. Have to go back in two weeks to hopefully get a better idea, they didn’t give me a due date yet because of that, and by that timing it’s just about impossible for me to have conceived when that would suggest because other than the sexy time timing😜 and continued opks just to make sure, I got my BFP 3 days after what they suggested would’ve been conception. We did see and hear the heartbeat, 144, but as this is my first pregnancy I’m nervous about it measuring small so early. Trying not to worry too much, has anyone else had this happen? Pic included bc small or not I think it’s adorable haha ☺️ in case anyone can’t tell cuz I sure couldn’t, the top thing is the yolk sac and the bottom bean looking thing is baby