I've been using the last of my OPK's this cycle along with my CBFM. I usually have a 28 day cycle and I got my peak on CD16 & 17. Today is day 18 and I got a high although my OPK says I'm still surging. Is it likely that I haven't ov'd yet? Will this mess up my cycle? Also when am I 1DPO? I'm so confused!