I would say Feb 6th encounter Hun . I'm sorry if that's not what you wanted to hear . I know how you feel on this subject . GOOD LUCK
It all adds up to the February 6 person.
An ultrasound looking at your actual embryo, with a doctor reading the results, is more accurate than an online calculator based on your last period, especially if your cycles are irregular. What due date did the doctor who read your ultrasound tell you?
Most likely the guy on February 6. Even with the slight margin for error a ninth-week ultrasound can have, it all points to the later guy, not the January 22 guy.