To start, I am 18. My boyfriend and I have been sexually active, and every time we have sex, we wear a condom, I'm on birth control, and he pulls out before he ejaculates. I take my birth control around the same time every night. My period was supposed to come 3 days ago and it still hasn't, and I was wondering if I should worry about this or not because it might just be late? I am under stress but not a massive amount, I haven't gained or lost a big amount of weight, and I haven't done strenuous exercise. I'm just worried I might be pregnant, but what are the chances I am? Thanks for your help in advance. This is really scaring me.

Give it another 10 days and then test again. It is possible that the condom failed, he got semen in you, and that your hormonal birthcontrol failed. Stranger things have happened here. It could be the stress, it could be sickness, or drugs. All you can do is wait and test if you don't get it. I would refrain from sex until you have this all figured out though.