OPK line strength fluctuate throughout cycle? New to this.

[free_spirtd]

I have never used OPK's before, but since I got married last month, we have been getting more serious about planning for TTC. I figured I should know if I am ovulating and when, and well....if. I had a chemical pregnancy last spring due to a "whoopsie" moment, but we have been using the pull out method for BC for 8 years. So I received a +opk CD 11 & 12, then they faded back out. I randomly tested after the negative until it went pretty much all white. I tested with one today (AF due, but only 2 spots for the day, but not abnormal, so thinking it's coming tomorrow) and it was slightly darker than the faintest I've gotten. Does the darkness of the line represent the quantity of LH in your system or does it just mean it's present? Thank you in advance! Also, the pic is my progression to a positive (I didn't save all of the tests) but the 3rd test down from the top is tonights to show where it falls in the darkness). I know it's not positive, but just wondering about the quantity.