In the current scenario, if you are not on any pills now and are sexually active, please repeat tests for pregnancy
, a clinical exam by a specialist and a sonogram, preferably trans-vaginal. Since urine and blood tests have been negative, you would need exclusion/confirmation through sonogram. If pregnancy is excluded, other possibilities are the hormonal
imbalance secondary to pill usage which results in absence of cycles in many or the weight gain. Hope this helps.