Femara/Letrozole

I’m currently Cd 13 on my 1st round of femara 5mg. I’ve been doing Opks since day 11 and still haven’t ovulated. On my 1st round of Clomid I ovulated on day 14 with my surge being on day 13. I’m starting to feel discouraged. Has anyone ovulated on Clomid but not Femara?