IN NEED OF HELP!!!

My boyfriend and I have been together for 5 months and have been sexually active all 5 months (we were friends before getting together). Well, he stopped using condoms about a month or so into our relationship and has just been pulling out. I'm not on birth control, but we've been in the clear so far, until this past week.

My period is 4 days late, but I have taken two tests, one the day my period was supposed to start (it's never late), and one this morning, but they both were negative.

Any ideas?