Baby measures less on last appointment, Glow says 12 + 1

Hi, I have a concern. Glow says 12 weeks 1 day, dr. who did the ultrasound for downs says 11 + 5, my dr. says 13 weeks.

Date of last day of last period was 16.9. on Glow, by that it means my dr. is right. I had sex only on my fertile days that month and my period dates were transferes from Glow ovulation. I don't understand why is Glow telling me it is 12 weeks?

Also, I am so concerned that the baby stopped growing because the other dr. says its only 11 + 5. The picture is the one that measured 11 + 5.

Baby was verry active during both dr.s ultrasounds.

I am spotting on and off from week 6 and I allready got used to it, but now I am sooo worried.

Did any of you have similar experience?

Tnx in advance!