18 DPO - AF 1 Day Late - Fed Up

Starting to become fed up now. At 16DPO I got a negative hpt. Today I have an opk which is really dark and almost positive. Last night I wiped myself and had brown spotting, thought a period was on its way but nothing ever since then, just quite heavy CM. Don't want to take another hpt because I don't want the heartache of another negative this cycle. My body is so hard to read what with the irregular periods, up and down opk results daily and constant symptoms. I have no idea what is going on. Has anyone else been like this?