Help!

So I got a positive pregnancy test 2 days ago, but whenever I try to calculate my due date based on my last period which was October 12th, all my apps say i’m only 2 weeks pregnant and baby hasn’t been conceived yet. I’m so confused?! I’ve taken 4 tests and they’re all positive. I did ovulated earlier than I thought this month, I ovulated (I think) on the 20th. How far along do y’all think I am?