OPK help

Hey ladies,

My husband and I have been trying for awhile. I took an ovulation test on the 15, 16 and the 18. The first test showed the test line as being dark, but not as dark as the control line (pretty closer though), also my cm was pretty thick. We had sex on the 15th. On the 16th, I took another opk, and this time the test line was much darker. I took this as I was officially ovulating. Unfortunately my husband worked the 16th and 17. On the morning of the 18, I took another opk... This time the line was much lighter. Anyways, I noticed tonight that when I went to the bathroom there was very faint spotting on the toilet paper. I am 3 days away from my expected period. I do not want to take a pregnancy test just yet, because it always seems like I start only hours after I take the pregnancy test. Any ideas on what might be going on? Possibility of being pregnant? Any input is greatly appreciated!