What Causes Dysfunctional Uterine Bleeding?
Don't wait.
Detailed Answer:
Hello and welcome,
Given that you have been bleeding heavily for 21 days, I recommend not waiting any further to have this dysfunctional uterine bleeding evaluated. If you go in now, they can do a pelvic exam and see what might be going on. They can also give you medication to shut the bleeding down, at least temporarily. And they can check your hemoglobin/hematocrit while you are there to see if you are developing anemia too. I would not wait as apparently it is not stopping on it's own.
There are many causes for dysfunctional uterine bleeding and menorrhagia, including hormonal disturbances in estrogen and progesterone that can be related to stress or other problems, thyroid abnormalities, uterine fibroids, polyps, etc. So best to go in and have this looked at now. Don't wait.