OPK question

🤨 so... took an OPK/ LH test yesterday (day 13) at 5:33 pm and the test line was just slightly less dark than the control line, took another test at 10 pm and the test line was the exact same color as the one before, took another one this morning (day 14) at 10 am and the test line was the same color as the 2 before, took another today at 8pm and the line is not dark at all and barely there. Did I miss the surge... do y’all think it could have happened before day 13 or could it have happened between the hours of testing? FYI- I’m super regular, always have a 28/29 day cycle and usually I get my surge on day 14.