PCOS, Clomid and ovulating

Julia • Married and just starting ttc! Trusting in the One who makes all things possible! ⚓️❤️
I took Clomid almost 3 weeks ago and had plenty of bd'ing. Yesterday I went to my dr and had a blood test to see if I ovulated. They checked my progesterone level and said based on that, I didn't ovulate.
I figured I wasn't pregnant (this is our first time trying and I haven't ovulated on my own) but how can they tell I didn't ovulate this week if my peak fertile time was last week?