There was condom slippage after intercourse. Can this lead to pregancy?

Hello doctor,

I had sex with my partner two months back using a condom. After ejaculation, she was getting off from me, and as she got up, the condom slipped off. I, however, pulled it out of her. When I did this, the semen leaked on my leg. As she was on top of me (due to gravity), all the semen fell on my leg. At that time I was 80 % confident that no semen had gone near her. To be careful, I recommended her to take the morning after pill, and she took it 12 hours later. Approximately eight days after sex, we did a pregnancy test which was negative. She usually has her period around the 17th of the month. Her period is now four days late. Can you advise why this could be? This is the first time she has taken any pill.

Thank you doctor,

It has now been almost 13 days since her expected date of next period. We are both anxious and planning to take a pregnancy test tonight but are very scared to take it. My partner has been going through a lot of stress due to work, and I am trying to remain positive because we used a condom during sex that did not break (it slipped, but I am 80 % sure that all the semen stayed in the condom). Her last period was a month back, we had sex ten days later, and she has a 30-day cycle. So, according to online fertility checker, she was not very fertile. She took EllaOne after 12 hours of us having sex. She has no other side effects apart from not having her period yet.