It's always tricky when you have THAT long of a cycle, I agree. Your mind starts to play tricks on you. I had a thyroid issue of a slow working thyroid and a hormone imbalance of too much estrogen production which gave me periods spaced out every 3 to 4 months. It was bad because I'd get pms symptoms at 3 weeks like clockwork and it would last until I got my period months later. I kept taking pregnancy tests too. You can have issues that cause this unpregnancy related and that is probably you. Those pregnancy tests are pretty accurate and it sounds like you confirmed negative at your doctors office. If you don't get your period by 3 months (which you are close), then go back to the doctor for some blood work.
As you get more serious with trying to conceive and they can't come up with WhY you have such long cycles, you may need to work with your doctor to obtain pregnancy. Sometimes they add progesterone to trigger a period and clomid to pop more eggs. But that's all to be dealt with by your doctor.
At 3 months, no period AND you are trying to conceive, I'd go see your doctor for blood work. Let me know how that goes as it is almost that point!