It is quite likely that you are not pregnant, given the prolonged duration and negative pregnancy tests.
There are many other reasons that can produce amenorrhea (lack of periods), and I would recommend that you get evaluated by an ob/gyn for the same.
Some of the common reasons include,
Stress, reproductive hormonal problems, thyroid problems, Polycystic Ovarian Disease, excessive exercise, weight loss, and some medications.Read more herehttp://www.mayoclinic.org/diseases-conditions/amenorrhea/basics/causes/con-20031561
Dr Gupta, MD
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