They easiest way to tell whether you are ovulating is to take your temp on a special bbt thermometer each morning before you wake up. There is a pattern where your temp should be about 1/2 degree higher after you ovulate. This can tell you after you ovulate, whether you timed bding right.
You can also take tests in an ovulation prediction kit (opk), which cost $15-40 per month. These tests tell you when you are in a fertile window 12-48 hours before ovulation.
If you have been trying for two years with no luck, then go to the doctor. Your doctor can refer you to an infertility specialist who can run lots of tests on you and your dh.
I know several people who had kids in their 40s.