Help with OV sticks

[Coffee]

Sorry girls, i have no piccies, but need your help.
I have been using Tesco ovulation sticks. When i did the test yesterday i put it on the side and then completely forgot about it! 2 hours later i remembered i hadn't checked it! Doh!! So i had a look and it was showing positive (test line was definitely darker than the control line). I started worrying then that it might be a false result as i had left it so long???? Are OPKs the same as pg tests? Does the line get darker after you have left it? A couple of hours later, about 10pm last night i did another and the test line was almost as dark, but just slightly fainter than the control line....
What does all this mean???!! Should i take yesterday as a positive? I did another this morning and the test line had gone back to being faint.

 

[2016]

In my experience it doesnt really change much with ov tests. I still have my last positive one (its now 3 weeks old yuk!) and it still looks just as positive as the day it was done.....its dried out of course but the test line is still darker than the control. I would say take that as your positive and get BDing!

 

[MissAma]

I'm sorry I didn't see this any earlier. That sounds like a definite positive and no, they are not as strict on time limits as HPTs!