Early ovulation and spotting on letrozole

IUI #3. We switched from Clomid 50 mg to letrozole 5 mg this cycle, because last two cycles my lining has been a little thin (6.2 cm and 5.6 cm). A day and a half after finishing my 5 days of letrozole, I started spotting and still haven’t stopped. It’s cycle day 12 today and I went in for my monitoring labs and ultrasound and apparently I had ovulated early.

Doctor told me it’s probably peri-ovulatory spotting… but I’ve never had that before. She told me spotting after letrozole at the doses and timing I took it is not likely.

We’re switching back to Clomid for next cycle but it sucks to have missed this cycle due to early ovulation.

Wondering if anyone else had a similar experience with letrozole?