Ovulation confusion


So I’m super regular, cycle is 27/28 days, usually ovulate every 13/14 day confirmed with opk. Today would be day 13 for me and literally completely blank opk test?? I’m just confused as to what’s happening, I’m testing morning and evening. I’m using pregmate tests.. just based on how regular I typically am idk if I should keep bd this week when the app predicts, keep testing? Or what it could be, any input is helpful! Thanks