Welcome to HealthcareMagic forum.
Since you have been on pills , if you have been taking it regularly without missing them , there is very less possibility of pregnancy
The symptoms you present with are non specific for pregnancy,through pregnancy may be a possibility, I will associate this more to the pill effects as these do cause hormonal
changes and breast changes .
You could just do a URINE PREGNANCY TEST and confirm if your pregnant
The brown discharge I feel is an indication of the next cycles.
Wish you good health