Why is AF so late (No pregnancy) ?

Hi girls!

I start to wondering what is happening with me! My AF are 4 days late. I never been late like that for the past year. And, I dont feel like im going to have my AF soon!

My stress level is Ok. I have been really more stress previously and it did not affect my AF due date.

No change in my sleep, routines, food...

But:

6 days before AF, I had a "itchy problem" probably a yeast (extern one). I took antifungal and it when away. Could this explain why Im late?

Im ttc since 13 month. Could I have problem with my fertility?

Have you ever experience something like me? What was it?