What Causes Delayed Period, Heartburn And Sore Breast While HPT Is Negative?

Hi,

I have a question that has been kind of bothering me. I haven't had my period all of november. I do somtimes have irregular but lately its been coming on every month. I keep having syptoms as if it was goin to come but it didn't. About a week ago I had a slight pink discharge so I tried to use a tampon, nothing. I've also have had sore breast and bad heartburn. Also I've had some cramping here and there. I've been extremly tired but it could have somthing to do with my schedule. I also took 2 hpt test both neg. one was a week after I had unprotected sex and the other made 2 weeks. what is wrong with me? should I be concerned?