Many thanks for your question. Very heavy menstrual bleeds and blood clots should not be ignored, and the cause of all this does need to be determined. It may be in-part be due to the sterilization, but this should not be happening to this extent. It is essential that you make an appointment to see your gynaecologist so that he can examine you fully and pinpoint the cause and treat this extensive bleeding. There is medication available for extensive bleeding like this, but it is scheduled pharmaceutical medicine and can only be prescripted by a medical doctor.
You are quite right to query the idea of your doctor putting you on a contraceptive when you do not really need it for this purpose. There are other approaches to bringing your cycle back.
You do not mention as to what type of sterilization you have had - did you have a total hysterctomy, or a partial hysterctomy, or was it simply a matter of having your tubes tied (i.e. when the Fallopian tubes outside of the uterus are tied so that in the transportation of sperm, the sperm does not reach the ova due to their pathway being blocked)?
I still recommend that you see a gynaecologist to be reassessed and examined. Once the cause is determined, you could consider taking VITEX AGNUS CASTUS BERRY by Viridian as x1 capsule, 3 times a day for a month - this is if you did not have a full total hysterectomy.
Please make this responsible appointment soon. Let me know how you do and that your problem was resolved.
Warmest regards, and many thanks once again for your question.