That's what you think.
It may well be that you've had it asymptomatically.
Unless you've been testing assiduously and every couple of days - certainly more often once week! - you may well have had it ... I was C19 +ve for maybe 48 -72 hrs back in March, which is documented
here in the other Covid thread ...
I have three friends who have had it asymptomatically - one was tested prior to hospital admission for elective surgery, one tested as a polite and socially-responsible precaution before going on a family visit to someone who is severely immunocompromised and one tested after being exposed extensively to someone who, a couple of days later, became quite ill with C19. All three tested +ve and then waited for the symptoms to arrive - which they didn't.