What are my chances of being pregnant?

I don't know the exact details but I think no matter what time in your cycle you ovulate, you will have your period 2 weeks later. I read a bit about this a while ago, I'm not a professional so don't take my word for it. But I learned through reading the only thing that stands to vary is the time between your last period and next ovulation. If you used a condom and it didn't break you are at extremely low risk of pregnancy. A negative pregnancy test such as first response can predict pregnancy at a very early stage I think as early as 3 - 5 days after your missed period. Late or missed periods are not uncommon in people who are not pregnant. Wait it out a week or two and take another test but don't stress yourself out so much, condoms are very effective.