different due dates?

jennifer • mommy of 1 girl💕 & 1 💙boy🧸

my first ultrasound done on may 10 2019 said i was due on jan 2 ,2020 i later paid out of pocket couple days later to have us pics that us said jan 6 my ob says jan 8 ? but my last cycle was march 22-28 i also have irregular cycles on my last 3 ultrasounds 8wks,12wks&20wks im measure a week ahead whos right ? 3 different opinions from different places