Help!!!! I'm confused and concerned tti

Ok So I am trying to conceive.  I have checked my temps and monitored my ovulation.  I inputted info on here and was supposed to ovulate last thrusday. I did bd and everything in the books. Last night I felt weird so for kicks n giggles I took an ovulation test to see what's up.  It came back positve. I could have sworn I already ovulated a week ago.  My af is due in on the 18th so idk what's going on.  Did I just ovulate super late? Help!