Is it possable to not show a positive pregnancy untill later in the pregnancy?

Im on my third pregnancy on the second one I had a MC but anyways, In my first pregnancy I was 6 weeks when it showed up very clear on a test. Second pregnancy at 5 weeks it was a very very faint line (kinda thought i was looking too hard at the test lol) and in this third pregnancy I took a test and it was a very clear positive and they are telling me I was 2 weeks then!! Which is a huge shock to me since the others took so long to show up. I still think they have my due date wrong cause that seems so early to show up so clear on a test but I guess I will find out for sure if they are right next week when I have my 20 week ultrasound : ) AND good luck hope yal get your baby, me and my husband were the same way when we would take test and they said ; )