Myself (18) and my girlfriend (also 18) had unprotected sex the day her period ended. I figured she wouldn't be fertile and I'm pretty sure that I came in her vagina. Is it still possible that she could be pregnant. Also this was 2 nights ago and she plans on taking the plan B pill today. What is the likely hood of her getting pregnant?
There is a chance of pregnancy.
The thing to remember is that your sperm can survive up to 5 days in her vagina. So, even though she may not have ovulated yet, she normally would sometimes between days 11-16 of her cycle. Day 1 is when her period starts.
Plan B is probably a good idea.