My last cycle was June 22nd 2019

I calculated it with some friends and my conception Date is JULY 6th

I took a pregnancy test August 2nd doctor confirmed pregnancy August 7th my app and a few helpers and me said im suppose to be 7WEEKS and 5DAYS today!

My doctor said im 6 weeks and 4 days but that doesn’t sound right at all because i know the dates of everything from my period, the days we had sex, my missed period in July and so on. So can the doctor be off sometimes? I haven’t had a ultrasound yet.