I’m confused 😩

I had my period on 8/19-8/26 and according to opk i ovulated 9/13. Wouldn’t the tww start from there? I went online for fun to calculate my due date if i were to get pregnant this cycle just for fun and it says that by this time i should be almost 5 weeks pregnant, but I’ve been getting negative tests back. So im confused. Should i keep testing or just wait for my next cycle to start again?🥺😩