"what could be the cause of having extended periods? I never have cramps and it is not painful, but my period last much longer than what is normal. It can last for up to 3 weeks at times where it will be really heavy on certain days and barely there on ot

When . When you have irregular periods, you likely have anovulatory cycles resulting in dysfunctional uterine bleeding. This means that you likely do not ovulate every month like women who have normal menstrual cycles. When this happens the uterine lining builds up and begins to shed (bleed) in an abnormal and inconsistent pattern, just as you described in your post. The reason behind why you are irregular is a much harder question to ask. Commonly a condition called pcos (polycystic ovarian syndrome) is to blame. Although you do not fit the typical picture (overweight, excess hair) it can still occur in thin women. Ask your doctor to check an fsh, lh hormone level. Also a prolactin and TSH level should be done as well if not done already. To make your life easier you should consider taking birth control pills again to regulate your cycle. Best of luck.