Talk to Gynecologist on Heavy Periods For More Than 21 Days

I always had irregular, painful periods, from the very start... Most of the times, my periods last long than 10 days, sometimes they are absent for some months, and sometimes my periods come very earlier like on the after 10 days my periods start again..... This time, at 21st day, they are not stopping even though I've taken medications for urinary tract infections also and also some periods regulatory tablets... But nothing is working.... My bp is very low and most of people told me that it is because of the stress and anxiety and study... Because i am preparing for a compititve exam and they told me that it is not a big problem just because of the study and pre exam anxiety.... Plz let me know as if it is not a big problem....