When is the right time to test?

Here's my story. I'm on the pill, and I was on antibiotics at the first of the month. I also missed a few pills. We have had unprotected sex (and it wasnt like I didnt tell him about it, he knew) and my period was supposed to start last week and it still hasn't came. I tested twice earlier this week (Tuesday night and Wednesday morning) and both tests were negative, but my friends think that I need to test again because I've been showing some early pregnancy symptoms (bloating, boobs are a little bigger, slight cramping, nausea, lower and upper back pain, and I have been super emotional about small things that used to never bother me.) I've had a little bit of a brown discharge too. So, is it still possible that I may be pregnant and if so, when should I test again?