REALLY DESPERATE FOR ANSWERS

Desperate answers needed: My girlfriend and I often mess around and do stuff with close on. (Sort of like humping) But yesterday we went further so I did not have any clothes on and she only had panties on. This went on but then it slipped inside which was unexpected. I proceeded to reach a climax and when realizing what was happening I clenched the muscles off to stop any from going in a pulled out. My fear is that when I clenched some definitely went in. Be it precum or the real stuff. We are teenagers and can't afford to have a baby. I went to get her a plan b pill and she took it about 4 and a half hours after the incident. She reported a mild cramping in her abdominales an hour after taking it. It is currently the next morning and she said she feels normal. Is that a good thing? Also,yesterday was exactly 1 week away from her supposive period day. What are th chances that she gets pregnant? What can you tell me of the situation? We are both so worried . If she has her period in 6 days or just let alone her period, does that mean she did not get pregnant? What should we watch out for and what steps can we take to ensure no baby?
I heard that if an orgasm is reached, pregnancy chances are increased. She did orgasm.