Do lines slowly get darker when getting closer to ov?

[Ley]

I'm on CD 13 but my cycles are all over the place since coming off birth control pills so I have been testing since about day 6. I always test in the early afternoon.
Well right from the first test I was getting faint lines, they stayed the same though until todays test which was definitely darker. It wasn't a positive but was noticeably darker and the right side on the line was almost as dark as the control line.

I was just wondering if this is a build up to ov?

(I'm a first time opk user, can you tell? lol)

 

[camerashy]

yep if the line is nearly as dark as the control line id say u'll ge a def + opk in the next day/2.....get bedding , good luck

heres a pic of my opk past 2 days .....1st one: cd10 (neg @11am)
2nd one: cd11 (+ @2pm)
3rd one : cd12 (+ @ 10 am)
4th one: cd12 (+ @4pm)

the 4th even thou is positive is getting lighter and is catchng the very end of the lh surge,
i also used the cb digi opk.....got a smiley face along with the 2nd and 3rd opk strip on pic but was neg (no ) with the 4th opk strip

so for me ov day was today , hope this helps

also i felt really crampy today !!!!