When I had my first kiddie (she's 8 now) the Doctors kept giving me an original due date of mid November, (she was born mid Dec - bang on time as it turned out). The Docs assumed I had ovulated 14 days after my last period (they would NOT listen to me when I told them how irregular my periods had been before the Pill. I'd come off it and only had one Pill free period before I got pregnant, so they were still going by the 28 day cycle).
Turns out I had fallen pregnant nearly 5 weeks after my last period!! And yet, with my son, I came off the Pill, had a period, started trying and had painful boobs and pregnancy symptoms in a fortnight!! Go figure.
Do you get any pain shortly before a period? Some people say they can feel the ovulation!
If you are trying for a baby, in my personal opinion, just keep with the sex. If your ovulation is "outside normal cycle" then you may miss it by only trying on the days you think you are. Do you know what I mean? Good luck, if you are trying. I hope you can figure it out.