Late period on letrozole normal?

This is my first letrozole cycle. I did 2.5mg cd 3 threw 5. Then 5mg cd 10 threw 15. I am now on cd 35 ( period is 4 days late) and all my pregnancy tests have came back negative. I'm not having any pms symptoms at all. Not sure what to think. I hope this didn't mess my cycle up.

Vote below to see results!