No Periods, Stopped Birth Control, Heavy Discharge, Back Pain. Negative Pregnancy Test. Opinion?

I m 19 years old, I was on birth control for a year maybe and stopped taking it the end of May. I bled twice in June, the first time very lightly for 4 days and then a second time, two weeks after, more normal and for a week which was back to normal. Today it has been 48 days since my last period. I ve gone a month and a half without having my period. I ve also been getting a lot of discharge the last month, it s normal color and everything, just heavy and constant, which isn t normal for me. I ve also been having a lot of back pain . I am sexually active but I took a test and it came up negative so I m not sure if it was a false negative or if I m still not back on my regular cycle or not. I figured i would be back to my regular cycle now since I ve been off the birth control for 4 months now. I could use a doctors opinion