Two weeks = 14 days

Took a pregnancy test. 
Positive.
Went to the doctor. 
Ultrasound. 
Saw tiny heartbeat and a 9 week, 2 day-old baby. 
Due date: July 17th
Belly grew.
Felt small kicks at 16 weeks. 
Sure they were kicks. 
Stopped feeling kicks for 48 hours. 
Called doctor.
Scheduled ultrasound for same day. 
Saw baby. 
Saw heartbeat. 
Took a deep breath. 
He was okay.
Oh yeah. 
Found out it was a boy. 
Smiled and called parents. 
Confimed boy name.
(No, not telling.)
Due date "unofficially" read July 9th. 
Talked to doc. 
He says stick with first due date. 
Back to 17th.
Belly grew.
Feet swelled.
Gained weight.
Routine ultrasound today at 21 weeks. 
Saw baby boy again. 
Saw heartbeat again. 
All organs present.
Baby measuring big. 
1 pound 6 ounces big.
Baby book says 21 week old babies usually don't even weigh 1 lb yet.
Thought I was 21 weeks, 3 days. 
Ultrasound "unoffically" says 23 weeks, 1 day. 
Am I reading it wrong?
No.
Due date "unofficially" reads July FIFTH. 
Told to stick with first due date unless there is a 2 week difference.
There is a 12 day difference.