Bit confused

Ra

This is first month <a href="https://play.google.com/store/apps/details?id=com.glow.android">tracking ovulation</a> with the tests. My app predicted I ovulated on day 14 however the test showed a faint line on day 14, a line darker than the control on day 15 and faint lines on day 16 and day 17. Does that mean I’ve probably ovulated on day 16? Am I still fertile days after the test first started showed the LH surge is the line is very faint?