Am I or am I not

 My boyfriend had finished in me four different times. On my ovulation day, two times two weeks ago. Well you get the point. Anywho, we went out and bought tests yesterday and I only have one left. I would've taken a total of seven, catch is; every single one of them besides one have all came back saying "Not Pregnant." We bought the expensive $17.00 ones that tell you how far along and what not. So now I'm just super confused, was the one test a fluke? ​