My cycles have always been 26 days. Until last month when the doctor put me on progesterone to lengthen my luteal phase. My cycle went for 31 days, and it was amazing! This month though, I did not get a positive OPK so I called the doctor and they recommended I get my progesterone checked on the CD 22 to see if I ovulated. But today, which is CD 21, AF showed… Any ideas as to why this cycle is so short?