Is It Okay To Take Regestrone Now After Unprotected Sex When My Period Is Delayed?

Hi , My periods is regular and in July month it was on 13th and in aug it was delayed to 18th . In sept it s been 22nd and still I did not get my periods . I always have protected sex but my bad on 21st sept it was not a protected one . Could you please suggest if it s ok to take regestrone now or not ??