Hello, has anyone had a similar situation? 3rd day of delay, I underst...

Hello, has anyone had a similar situation? 3rd day of delay, I understand that it might be normal, but for the past year my cycle has been regular, these days come every 28 days, lately I haven't been sick at all, there was no stress, maybe some malfunction in the body, but yesterday and today I did tests, both negative. Has this happened that tests didn't show pregnancy? I know that you can go to the hospital, have blood work done/ultrasound. But we live in a village, and to the district polyclinic you need to go by appointment, it's practically impossible to call the reception, and on the ultrasound you can't book an appointment.