Yes, because "pregnancy" has traditionally been dated from the FIRST day of the last menstrual period.

(I'd like to know more about why that tradition hasn't been updated to fit the facts, but I'm not saying you're wrong.)

Ovulation doesn't occur until 2 weeks later, then there has to be both fertilization and implantation, and as you say testing positive isn't going to happen for another 2-3 weeks, which of course is what turns a "6-week" abortion ban into a 1-week ban.