First round of Letrozole and lots of questions inside 🤨

Ok so this is my first month. I am currently on cycle day 23. I could have swore I ovulated CD 18. I had a positive opk that day as well as CM where it should’ve been for ovulation. This is the first month I have consistently tracked my bbt and I am just so lost. According to my temps...it looks like I didn’t ovulate. So I am just discouraged and confused at this point. I have hypothyroidism if that helps. But I have been taking medication for it and got my levels checked in April and they were normal. Does this mean the Letrozole did not work? Can my bbt be off? I take it orally around 4:30-5 almost every morning