If she's stressed out, over exercizing, or not eating (Trust me, not a smart thing to do, if that's the case turn it around now before it turns worse) then that is why it could be late. I've heard that having sex can also make it be late sometimes. And so can being pregnant of course.
Go out and get a pregnancy test. I don't remember whether it is before or after your period that you are more likely to get pregnant...maybe someone else can help with that.
As you know, condoms aren't 100 percent effective, and you should be using two kinds of birth control (Trust me on that one too) But no where in your post did I read that you used any kind of birth control. Big mistake if that's true, because there is pre-cum, which contains the same stuff as when you actually do cum, and yes, that can get her pregnant.
Good Luck
xx22xx
Posted: 27 Sep 00:33