Timing is critical for successful conception. And egg is viable at most for 12-24 hours after ovulation, so it's very easy to miss. While there is variance from woman to woman on an individual level (like changes in vaginal mucus, body temp, or physically feeling ovulation aka mittelschmerz), one of the best ways of tracking is measuring Luteinizing hormone (LH). As your body prepares for a potential pregnancy, LH gradually rises as eggs start to mature, surges, then releases (usually) one mature egg from the ovary after LH begins to fall.

For some women, this sequence of events can happen very quickly, slowly over several days, or rarely twice in the cases where an egg did not release and your body surges again. Inseminating multiple days, usually before peak, during, and right after make sure that sperm cells are raring to go as soon as the egg is available. If you can only inseminate once, you're best chances are on the day LH peaks. The reason is two fold. First, while sperm live 2-5 days in the environment of the vagina, most of those sperm really survive 2-3 days. Sperm will become less viable as the days go on, meaning less chances one of them is strong enough to penetrate the egg. Second, sperm have to go through a process called Capacitation. Capacitation is the process in which sperm become capable of penetrating an egg, which can take about 10 hours. That means, 10 hours are spent with sperm just getting set up. If this step is still happening after the egg is released, it may be too late for fertilization to occur.

If you haven't had success, but haven't been tracking, my suggestion would be to start with LH strip testing. With that, you can gain more information about your cycle and/or detect changes that may not have been noticeable.