Hello, I'm not a woman so I'm not sure I should be posting here but I figure this is the best place to get answers. My girlfriend and I had unportected sex the day her last period ended. I did not ejaculate in her and the whole thing didn't last very long. I was wondering what are the chances of her getting pregnant from that? I would think it would be low because she had JUST gotten off her period and the was no ejaculation. We didn't even think about her being pregnant until one week later we had protected sex and the condom slipped off and we didn't know if any spilled or not. We were very worried so she took plan-b the next day. We thought that plan be was supposed to make you get your period but I guess if your not ready for your period it just stops you from releaseing an egg? So she didn't get her period after taking it. Today is 25 days from the start of her last period (her normal menstrual cycle) and she hasn't gotten her period yet. Should we be worried?

I don't think so. To be frank me and my husband always have unprotected sex after my period and so far nothing has happened *knock on wood* If a woman is stressing about her period etc it could delay it a few days (I was just a few days late as well and was kind of worried but it's all good now. Just give it a few days, because it can be normal for a woman to be up to a week late.
And you posting here is fine because you had a question about women's health.

Anytime you have intercourse there is a chance for pregnancy. Protection used or not.

Please read this sticky, particularly the one about pregnancy and withdrawal.