Hi!
If I was your doctor, I would suggest a few different options First, if you consider the FIRST day of your mentrual period to be day one of your cycle, then days 11-16 are typically the most fertile time. You can use ovulation predictors which are similar to pregnancy tests. You can also use something like our ovulation tracker:
http://www.medhelp.org/user_trackers/gallery/ovulationif you wish, to help you pinpoint when you are ovulating.
I also like to check a progesterone level for my patients, to be certain that ovulation DID occur.
Hope this helps!
Dr B