You will always have a second line as there is always some level of LH in your body What you are looking for is your LH surge, where the hormone suddenly rises a lot. OPK lines should be as dark or darker than the test line to indicate a surge. Your darkest so far seems to be day 10/11. However, the lines are not as dark as the test line (although some women find that they do not get a line as dark as the test line - but it could be that their surge was short (even though opks say 12 - 36 hours, some women have a very short surge of less than 10 hours) they missed it when testing), usually this means that ovulation has not yet happened.
Roughly speaking, you should ovulate about 14 days (known as the luteal phase) before your period.
Although they are expensive, Clearblue Digital OPKs are the best! They give you a smiley face to indicate LH surge - no line squinting! I conceived both my boys using them!
Good luck xxx