How many weeks am I?! Please help!

Janine • Mama to Sienna Rose + little pea due 10th Aug 2018

I just received my positive pregnancy test 5 days early! Wooohooo! I usually have a 36 day cycle (can be irregular).. my period was due on the 1st December and I ovulated around the 16th November. The first day of my last period was the 27th October. According to the calculator I am 4/5 weeks pregnant. But I ovulated 1 1/2 weeks ago. What do I go off of? Trying to figure out when to book my first doctor appointment