How do I know when I ovulated?

I'm 6 weeks pregnant went in for US doc couldn't find anything and my hcg levels were low, she said it might be early pregnancy or maybe will have MC
My last period was May 26, my cycles are regularly 30 days, had sex that got me pregnant on June 9
So given these dates, am I not 6 weeks?
idk how the ovulating dates work :/