I had my period on February 7th. my cycle is irregular by a few days difference, anywhere from 26 to 33 days. my average cycle is 29 days. Glow calculates that I will possibly begin my fertility window on the 16th which is cycle day 10. I only have one fallopian tube so my chances of conceiving is slightly less than someone with two healthy tubes and alternating ovulation. My boyfriend is coming over on the 17th and staying until the 19th. hopefully my opk shows a positive between those days.