Thanks so much for the kind words!
So, one of the common side effects of emergency contraception is that it can make your cycle wonky for awhile after you take it. And exactly how it influences your cycle can vary, and this time it sounds like it's might be delaying your period. With the pregnancy test, as long as you took according the directions that came with it about when and how to test, you can assume the result is accurate.
I do want to check, since it was unprotected sex, are you and your partner up to date on your STI testing? And are they someone you live with?