My Period

Amber
So, I'm on birth control, and I always get my period on the second day of the sugar pills, but I haven't had my period yet. Tomorrow is the last day of the sugar pills, and nothing, though I did have some spotting during the third week of active pills. 
I have been having sex, but I'm fairly certain I can't be pregnant due to the fact that I take my birth control at the same time religiously, and also the fact that I always use a condom while having sex and none have broken or anything. 
I know that most people would suggest that I go buy a pregnancy test just to be sure, but the chances seem so slim, and I'm also not to the point where a test would be accurate. 
I guess I just wanted to share this because I've been getting regular periods since I started birth control, so this is the first time I've skipped one in forever, and I have no idea what could be causing it.