Ovulation - due date confused :/

Okay long post ahead ,

So does HCG start going up after you ovulated ?

Does the clear blue digitals go off when you ovulated , not when your period started / ended ?

So scan has me at 8 weeks 1 day.

Period LMP has me at 9 weeks 1 day.

Did I ovulate 2 days after my period , or does pregnancy start from when they assume you ovulated say 10 -14 days after you period ended ?

I got a positive test and a reading of 3+ 12 days after my apparently "ovulation day"

Then blood tests 2 days later had me at 5+ weeks.

If I ovulated when the "assume I ovulated" wouldnt that make bub measuring behind by 2 weeks 6 days ? On an ultrasound ?