Inaccurate prediction??

So the calendar on here is telling me I should have had a period the first and last week of January but I missed the last week of January that I was suppose to have my “second” period. That would me as of today I’m 12 days late!! Usually I’m a couple days early or a couple days late but I’ve never been this late before!! Just wondering if anyone has had a similar thing happen to them with their period prediction on here? (I took a pregnancy test today, 12 days after my missed period and it was negative)