Question, when I went for my first ultrasound I was 14 weeks and 5 days, but baby wheary was measuring 16 weeks... I…

Question, when I went for my first ultrasound I was 14 weeks and 5 days, but baby wheary was measuring 16 weeks... I will be 18 weeks tomorrow, so does that mean that baby wheary will be measuring 19 weeks and 2 days? Baby Wheary was measuring a week and 2 days ahead so I'm wondering because I didn't understand at the appointment why my dr said I was 14 weeks 5 days but the ultrasound pic said 16 weeks