6 Negative pregnancy test

I've been seeing this one man for little over a year. With no protection we both agreed on it. Problem is I am 16 days late for my period. I've been pregnant before so I know all the symptoms. Here's the Dilemma I've taken 6 pregnancy test all negative. There has been a variety of different ones lines, and digital. And they're all negative. Does anyone have any suggestions. I'm thinking my next step is just go get a blood test I feel pressure in my abdomen. But there's no sickness none of that I do have massive heartburn though. So any suggestions I'm game.....