Ovulation testing

Hi everyone, 

My husband and I have just started trying, I am uber confused about ovulation, I know a sticky white discharge ( which I noticed earlier in the day) is a sign of ovulation but I did a test (first time using the digital ovulation test) and it is showing a solid circle no face? my cycle is 28 days last cycle. I am at CD 14. My app says I am meant to ovulate at 12. 

I am on metformin for PCOS to help my periods regulate so I am hoping it isnt too much different in next cycle. 

I wonder if I have missed ovulation or if it still coming up, has anyone ovulated later then day 14 on a 28 day cycle?