Okay, I had unprotected sex on the 10th day after my 1st day of period. And now my period is almost 3 weeks late. I did a first pregnancy test a week after my missed period and it was negative. On the 2nd week of my missed period, i did another test, also negative. Worried of not getting my period, i did another test (which it claims that it can detect early pregnancy as early as 3 days after the missed period), also the result is negative. Is there any chances of me getting pregnant after 3 negative results? And if it has been a month since i didn't get my period, and i did another test and it is still negative, is it safe to say that i'm not pregnant?