13 DPO bfn with no sign of period

I THINK I ovulated 13 days ago. It was a pretty strong second line on the opk and a bfn after my miscarriage on August 3rd. I've been testing using the tests that came with the opk and took a first response yesterday. All negative. Today I took a "rapid results" test with bfn. I had spotting for a few days about a week ago. No sign of AF. No tender breasts. Very sensitive nose. What do you guys think? Maybe I miscalculated ovulation? When should I expect a period or take another test?  :(