So in February I had unprotected sex. I felt weird, but got my periods in February and March, but they were light and shorter. I realized I wasn't pregnant because my HPTs also came up negative. Until last week, my lower abdomen (pelvic region) got hard and enlarged slightly. I would be 13-14 weeks pregnant, and have not received my period this month and I should've already. What's the chances that my stomach would do that when it's never happened before right when I would start showing when I'm pregnant. Is it possible even though my HPT's were negative?

While not common, it does happen for a few reasons, that a pregnancy doesn't get picked up on a HPT. Since your last cycles have been irregular and the most recent not showing, see your doctor about having a blood test and an exam to find out if it's due to pregnancy or something else.

That is more indicative of a digestive disorder rather than pregnancy. Regardless get checked out.

How has life been lately? Stress? Illnesses? There are a bunch of events that can cause irregular or weird periods. While that might not be the answer, it is something to think about.