Why do i get extremely heavy periods?

Many reasons: The causes include: hormone problems- lack of ovulation, for example. Anatomical problems such as fibroids, tumor, adenomyosis (the lining of the uterus called endometrium invading into the uterine wall), polyps, etc.

Many reasons: Heavy menses (menorrhagia) can have many etiologies (reasons). These can include ovulation issues, fibroids, cancers, adenomyosis, polyps, pregnancy and possible infections. It is not normal and should be evaluated by your gynecologist. Initial evaluation will include history, exam, laboratories, and ultrasound.