So confused....

So when I called to make my 1st doctor appointment they said I have to be 8 weeks, which makes sense. I was expecting it. So they asked for my LMP which I was also expecting, so I told them august 18th, but that I ovulated a week late. (So while my period will say I'm 8 weeks on October 13th, im actually not until Oct. 20th.) But she said they go off the LMP and not ovulation, which is fine, but then she put my appointment on October 6th........? So ill be 6 weeks according to ovulation and only 7 according to my period.......?

Should I call and change it?