As per your statement you have told some symptoms but your worry was not diagnosed. You bleed abnormally,tired, painful where?, Back hurts and you have remarkable loss of weight. Your grand mother died of ovarian cancer
where as your mom, and aunt are not having any problem. You have not mentioned your age. All the symptoms you have mentioned may be associated with an ordinary problem without cancer. But your complaints need investigations to rule out your worry
Even doctors could not arrive at a diagnosis after hearing your complaints and examining you clinically.
investigations are needed like USG, Xray, MRI
of spines and if needed CT abdomen and blood investigations to arrive at diagnosis. Till then don't worry and spoil your days. Consult a gynecologist, do the investigation and get treatment accordingly.