Any1 had this experience

[confusedmum]

Hi all i had a positive test on the 3 July two days later I started bleeding but it was just like a regular period for me lasted 4 days no painful cramps and not too heavy then after this my test was negative so after it had stopped I never had another bleed continued ttc I never had a bleed since July so I took a clear blue digital test on the 20/9 and it flashed up pregnant 1-2 weeks I went to visit my midwife on the 23/9 to complete my booking forms and book me for a dating scan she said it sounds like July was a chemical and then you had your period on the 5th July so we will put that you are 11 weeks.
My question is has anybody else had a clear blue weeks indicator be so wrong?
Thanks for reading have a nice day xx