It can be due to some hormonal
alterations in your body. Sometimes some pelvic pathologies as fibroids, cysts or polyp also cause such problems. You need to get an ultrasound
and some hormonal evaluations done to rule out any cause. It may not be associated with low iron, in fact your heavy periods
may be the cause of low iron for which you need to take iron rich diet as lots of green vegetables and fruits like apple, pomegranate.