Hi! I think you are on track with your suspicion about stress being at the root of your problem. If my patient called with your question, I would suspect that she occassionally has "anovulatory cycles" in other words, times when the hormones are out of whack so that no ovulation occurs. When this happens, the uterus sloughs of the lining irregularly in bits and pieces instead of all at once. This can cause heavy bleeding, prolonged bleeding, clots, bright red, dark brown bleeding, etc. To get down to the nitty gritty--the problem is a lack of progesterone, and I would ask my patient to take some progesterone. Medroxyprogesterone Acetate should be available in most countries!
I would also wonder whether my patient would like to go on oral contraceptives for cycle control--just for convenience.