T.W.
There are hundreds of things that could be going on. Yes you could have a failed tubal and a false negative and be pregnant. The odds are pretty low, but indeed possible. There are medical reasons that you could be missing your period, like the woman before said, you could be going into early menopause. There is also the option of stress. Stress can cause a ton of crazy symptoms, one of the biggest is missing a period. Who knows, but you do need to call the doc.
Good luck!