What Causes Delayed Periods And Bloating With Negative HPT?

Hi I'm 24 yrs of age, I had my last period on da 3rd of march n had unprotected sex wit my husband there after 4 2weeks. I had all the signs of being pregnant, I took a hpt and the results was negative, I'm still bloated and still there are no sign of being my periods. What's going on with my body. I need help.