Further along than I thought ???😕

Kelz

So I went to the early pregnancy unit this morning because I was experiencing some brown spotting, doctor confirmed everything was fine but told me I was 8 weeks 3 days instead of the 7 weeks 5 days I thought I was, meaning my duedate is now in Feb, I just wanted to know how is this possible???? I track all my periods using an app and I was like 99% sure of my timings.