High Fertility for nearly 2 weeks

I'm taking Meformin because I have never had a regular cycle and I have small cysts on my ovaries.  My cycle should now be 28 days, so I looked at the chart and started CB when I was meant to for a 28 day cycle.  According to the math and ovulation charts, I should have ovulated somewhere between the 9th and the 13th, but I never got a PEAK reading.  I tested today and it was still high and not peak.  I took the test once and got a low reading, but every morning since has been HIGH with no PEAK
What could be the problem?