What could cause daily menstrual bleeding for 1+ years?

I would assume you have iron deficiency anemia by this time and should take a daily iron supplement. Various factors can cause this and you should be under the care of a gynecologist. If you already have one you might consider obtaining a second opinion.

When bleeding that long, 1+ years on a daily basis, it is beyond menstruation, it is abnormal (Dysfunctional) . Besides risk of Severe Anemia- and other complications are heightened. This requires that One sees the Gynecologist as soon as possible.