My period is 2 weeks late, I've had three negative pregnancy tests and my cycle is regular HELP?

I'm 20 years old and have taken three pregnancy tests, one given by my Gynecologist, and they've all been negative. I've had a slight whiteish discharge that isn't yeast related as far as I can tell. I have been sick on and off since mid-May though. The sex I had was protected and the condom didn't slip or break. What's happening?!