There is a ovulation calculator on the babycenter website
http://www.babycenter.com/calculators/ovulation/
You just enter the day you started your last period and tell them how long your cycle usually lasts. From this information, they can tell you when you're most likely to be fertile over the next 6 months. Worth a shot, especially since you really haven't been trying that long. If that doesn't help, then you should definitely see a fertility specialest.
