Weight-loss Surgery and TTC

Okay. So I had weight loss surgery November 2013 and lost over 300 lbs. Had the surgery to have a baby. Because i was told I couldn't have one at 500lbs. I was never regular until 2.5 years ago. Have a 26-30 day cycle. This month im sitting at day 37 and nothing. Took a Dollar Tree test the morning after my missed period and negative. Gonna wait another day or so and buy another test... but has anyone had a negative test and turned out to be pregnant?