does this mean i still might be pregnant?

I'm 17 and I had drunk protected sex on April 10th, and then sober unprotected sex on April 16th. a few days later i had a pink brownish discharge that i've never had before and i could tell it deff wasn't my period, and it didn't last all that long and i was supposed to start my period the week after that, well now i'm 11 days late for my period and i went to my school clinic yesterday and they urine tested me but the test was negative. i'm not sure what to do now and any help or suggestions would help, please and thanks:)