First ultrasound- measuring two weeks behind

Hi everyone.

Had my 8 week ultrasound today, and instead of measuring 8w2d, I’m measuring 6w2d.

My periods are anywhere from 18 to 25 days apart, so it’s definitely not regular. I also breastfeed my toddler so they suggested that being a factor. Heart motion was detected but not enough to measure.

I go back next week for another ultrasound to see if baby is progressing. Trying to stay optimistic but hoping somebody has gone through something similar 🙁