When is my due date??

I know you’re supposed to go by your period but I know for a fact I did not ovulate during the week my calendar told me I did. I think I ovulated either the 10th, 11th, 12th of this month! I got my first faint positive on October 21st. The doctor drew my blood that day and it was level 17 so she told me I was literally a minute pregnant. Lol I got it drawn again that friday the 23rd and my level was in the high 60s!

I don’t know what to do because my app says I’m 4 weeks 6 days but my doctor said I was not that far