PCOS pregnancy - date confusion

Jessica
Hey guys,
I have PCOS and I'm extremely irregular. I go months between periods. So, unsurprisingly, I didn't bat an eyelash whenever I first missed a period.
My last period was late October (again, totally normal for me to go up to 180 days between periods) and I tested December with an at home pregnancy test, it was negative.
I tested again on Tuesday and it was positive. I took 7 more positive tests the past few days.
Has anyone gone through something like this? I have a doctor appointment Tuesday but I can't fathom being 13 weeks along and not having a clue. 
Thanks for your help!