Have you been on any contraception previously?! I know that it sometimes takes months before the pill has left your system and can take longer to get pregnant..
Timing sex for pregnancy has to be exact, there's a very small window of chance each month, so you have to be spot on to get pregnant. Using the apps and calculators to predict when you may be fertile aren't a very accurate way of tracking ovulation, so if you're using those, and having no success, your cycles are probably different from the "typical" cycle. I used ovulation predictor kits, OTC, and we got pregnant in about 3 months, they tell you when you're most fertile and most likely to get pregnant, and using a basal body temp. is even more accurate, so the two combined can really help track your ovulation. If you don't want to buy a bunch of things, or stress over kits and temperatures, just have sex every other day from cycle day 11-23. Lay flat on your back 15-20 minutes after sex before you get up to go to the bathroom. Remember it can take a normal, healthy couple up to 1 year to conceive, so if you have no success by 1 year, that's the earliest a doctor will test you for issues, some even wait 2 years with no success because they'll want you to try temping and OPK's before they'll test you, so get those started, and good luck, relax and enjoy it, don't make it a chore!
Have you used an ovulation predictor kit? If so, then you probably should go to your doc to be tested for any issues that may be causing the problem.