As your tubes are burnt and recently get negative tests for pregnancy, then your possibility of being pregnant is unlikely.
Besides pregnancy, other reasons of delayed period are ovarian cyst
, hormonal imbalance, stress/ anxiety, thyroid problem, wt gain/ extreme loss, irregular eating habits etc. Dark brown discharge may be due to vaginal infection
Do some initial investigations to rule out underlying pathology like USG pelvis, Thyroid profile, other hormone assay, blood sugar & prolactin
level etc. One vaginal swab test & urine examination are also required to exclude pathogens. So consult with your doctor at the earliest and take suggestive measures.
Avoid stress/ anxiety, take healthy diet with iron supplements
, do light exercise, maintain genital hygiene properly. Sore breast is due to effect of progesterone
hormone. Use tight breast support for discomfort and take prime rose cap.