gender & due date

Briana • 11•12•11 👶🏽💙 11•16•17 👶🏽🎀 6•7•21
I want to know what I'm having so bad but my doctor said I had to wait till I was 19/20 weeks & then I got my due date knocked back another 4 days I have no clue why so I should be 18w & 5d but according to this new dd I'm only 18w & 1d. I know it's not a big difference but Is there anyone that just said f*** it & still went by their old due date? My sons birthday is November 12th & my new dd is the 9th it's just getting closer and closer to his birthday which I don't want 😩 but if it happens 🤷🏽‍♀️I just want to know the gender faster. Thinking about scheduling it on the 19th