Opk newbie

Andrea
Ok so I tested on the 13th (cycle day 8) and it was negative but the test line was there, just lighter than the control line. I've tested every day after that and my test line is lighter than it was on the 13th. I'm now on cycle day 12 and my test line is very faint. Did I miss my surge?? 
Side note: I drink a ton of water throughout the day so I'm going to try FMU tomorrow and see if it's any darker.