Pregnant or may be pregnant?

i am a 29 yr old female i have had three kids since i was 20 my last was born new years last year after him i started on birth control i have been on it for over a year and a half and this month i had my normal period then 9 to 10 days later i start bleeding lightly with a brown dis charge is has been going on for 24 hours i took a cheap home pregnancy test it was negative and also i had some light cramping does it sound like i could be pregnant?