So frustrated!

So I usually ovulate around cd14 or cd 15, but my cycles have been a bit irregular, so I decided to start OPKs early so I didn't miss the surge... I had an almost positive on cd5 but assumed it was a blip as it was way too early to ovulate.... But now I'm cd18 and I haven't even seen a test line on my OPKs since cd5.... Just wish I knew what was going on so we would at least have a small chance!! 
Has this happened to anyone else?