How far am I ?

I have PCOS, Last period was on May 3rd. I Ovulated on August 22 and got pregnant. I got blood test done last week confirmed, first ultrasound scheduled for the 24, My Doctor told me she doesn't really know how far I am because of Cycles been so irregular, I guess we are going to find out by the ultrasound but I'm so confuse of how this works???? Anyone has idea of how far I could be by now?