Hi Im 20 Years Old I Have Been On Depo

Hi im 20 years old i have been on depo and i left it about 2 and a half years nu and i started taking the pill and then i got sick and the doc put me on antiboitics and i hade intercourse in that time but before that my period was regular and know im 1 month and 5 day late and getting brown spotting and clear discharge and now its only white like milky if any one can tell me what it can be i have done a prego test it came back neg....?can you please help me