New on OPKs

Help! When did i ovulate? Or did i even ovulate? And why do i only have 2 days of obvious second lines? The others are too faint? Thanks!

Cd 9 no line

Cd 10 no line

Cd 11 no line

Cd 12 faint neg line

Cd 13 darker but still negative line

Cd 14 barely there line

Cd 15 barely there line