I have just got back from the Drs after collecting my day 21 progesterone test. The result was 126 nmol, against the expected 16 -30 to confirm ovulation.
Dr says he has only ever, in 20 years of doing these tests, seen a result this high and the woman was pregnant. So with my head in bits I came home and did a cheapie test only to get BFN!! 
My cycles have been irregular but AF is due any time and I have been having very light spotting for the last few days. I usually get one day of spotting in the run up to AF so a few days is quite unusual.
Only other symptom I have had is incredibly sore boobs for the last week. Maybe I should give it a few days and test again.