Hello...
If you aren't ovulating what you are getting is just break through bleeding...not an actual period. Have you ever tried charting your temp to find out if you do ovulate on these unusual cycles? By no means do I think charting is for everyone, but it might help you to understand your cycles better. I charted and it helped me to understand that I wasn't ovulating hence no period, and the cycle I got PG it helped me to know that I was going to ovulate so we could time DTD better. Good luck!

Karen