Okay, help! I am a little nervous/worried. This is my first month using an OPK, and according to the instructions, I wasn't even supposed to start testing until CD 12 (which is June 12, tomorrow). Just for the heck of it, I took one on CD 10 and surprisingly, the test line was pretty dark. We did have sex twice that day. I was excited, thinking that it would get darker the next day and I was approaching ovulation. However, on CD 11, the line was weaker and now even more faint today. Surely I didn't ovulate before the CD 10, right? That seems a little crazy to me, and makes me worried considering that means I would've "missed" the majority of my fertile week. Is there any other reason that CD 10 would be that dark, and maybe I haven't ovulated yet? Glow was predicting that I wouldn't ovulate until the 16th! What the heck?!