letrozole and opks?

My letrozole dosage got doubled to 5mg this month. I always start my opks on cd7 and usually have a + around cd9. Im an early ovulater. Usually starting my opks on last day of meds, my opk line is relatively dark, but not this dark. Ive gotten faulse positives on clomid but not on letrozole. This one is almost but not quite. Is it due to the upage in letrozole maybe? Or could I really be this close? Not fmu or smu by the way