You should get some blood test
done like blood sugar,thyroid profile and prolactin
.Irregular menses can be caused by all of these conditions.But along with that you should also get an ultrasound
pelvis to rule out any pathology.You could have endometrial hyperplasia
causing you to bleed longer.The endometrial thickness should be measured.I suggest and that get some tests done and then see a doctor about drugs to control the bleeding.Hormones should help there.