IUI with Letrozole- what day did you ovulate? HELP!

Hi my supportive infertility friends!

I am feeling so down and hoping to hear something positive. We are doing IUI due to decreased sperm motility but throughout this whole TTC process I have never had any extremely obvious ovulation signs (opk, bbt, etc) but have been reassured by my GP and fertility doctor that I ovulate based on my cycle and blood work.

We were scheduled to do our first IUI this month and I took 2.5mg Letrozole to increase our chances. I had an ultrasound on CD10 and my biggest follicle was 11mm. She wanted me to come back CD13 (which was today) and my biggest follicle was 8mm:( she says the 11 may have “died off.”

Her plan is for me to return for another ultrasound on CD17 and she said if not large enough I will take a higher dose of Letrozole on that day (not sure for how long)

I am so bummed out wondering if I ever have ovulated consistently EVER and am wondering if anyone has shared a similar experience.

I need a pick me up bad! I am so discouraged!