In addition to the laws of niddah, the Torah details the laws of a woman with uterine bleeding not at the time of her expected time of menstruation. Such a woman is called a zavah, and she observes laws comparable to those of a niddah (see here). The Torah obligates the zavah to count seven clean days prior to becoming tehorah.
In practice, it is very difficult to distinguish between the zavah and the niddah with any certainty. (For example, there is a fundamental debate about how to determine the expected time of menstruation and when uterine bleeding creates the zavah status or the niddah status) Thus, for over 1700 years, halachah has considered all women with uterine bleeding as zavot, for whom seven clean days are obligatory.
It may well be, however, that there are ways to shorten the time you are spending in niddah without resorting to medication and without abrogating halachah. You may be extending the time you are in niddah by treating premenstrual staining too strictly, since not all stains make a woman niddah. You may also be delaying your hefsek taharah later than necessary. Washing out residual blood before the hefsek and making several attempts may help you get an earlier hefsek. More important, the hefsek taharah examination need not be completely clear. Some browns may be acceptable on the hefsek taharah cloth. Additionally, not all colors on a bedikah cloth or stain invalidate the clean days. Please review our articles on bedikot and stains for more information. We recommend consulting us or a local halachic authority before considering yourself niddah or evaluating a hefsek taharah that is not obviously red.
One last note: if you do experience a full ten to twelve days of blood flow, it would be worthwhile to consult your physician. There are also natural methods to shorten bleeding, of which we have received anecdotal reports, such as taking alfalfa, shepherd's purse, or flax seed. (Note that shepherd's purse is a powerful herb. It may not be used during pregnancy, and its use while breastfeeding is debated – a breastfeeding mother should not try it without the guidance of a qualified professional.)
Please get back to us with any further questions.