nervous

So.  I have a very irregular period due to the fact of me being on depo for 2 almost three yeears.  I've been off for a year now and get my period every 35 days ( strange and weird) this month I've had brownish color discharge for a week.  I took a pregnancy test and it came back I wasn't pregnant.  Is anyone else or does any ever have this problem.  I know I'm not the only girl with there lady part going through things.