My boyfriend and I are having unprotected sex for the past 4 months now and I did'nt get my period for 3 months now but every pregnancy test that I take shows that I'm not pregnant.How can that be?

Time to see a doctor... the tests could be wrong.

There are many women that never get an accurate result using an at home pregnancy test.

It's time to go to your doctor for a blood test or an ultrasound.