Would my low iron cause me to have bleeding for a month for my period?

No. It is likely that your month long period(s)are causing your low iron. Your period(s) are abnormal. There are many reasons for this, and is affected by age, number of babies, hormonal imbalance tumors in the uterus just to name a few. I would recommend yousee your gynecologist. .
No. Actually, it's the opposite. Prolonged or heavy menstrual bleeding is what causes the low iron levels.