I'm not irregular whatsoever. my periods are very consistent...

Just a few weeks ago(4/17/18), I experienced symptoms of lower back pain, cramps (terrible ones), a little nauseous, and anxiety.

I didn't really think much of it because it's what I usually experience when I'm a few days away from my period, but I didnt get it at all whatsoever. I took a test to ease my mind but it was negative.

My period is 6 days late (5/3/18)...

the day of my period I took another test but it showed as negative as well.

My boyfriend and I use the pullout method (I know..bad) and we have sex mostly every day.

Is it possible to have negative pregnancy test but actually be pregnant?