I have endometriosis and take the bc microgynon, it has a high hormone level but when i switch to a low dose bc i break through bleed constantly, ?

Not uncommon: Women have different thresholds of the amount of estrogen and Progesterone they need in their birth control pills to adequately provide adequate suppression of their own estrogen/progesterone cycling. That is why the pharmaceutical market has so many different types of birth control pills.

Common: Changes in the dose of pills can affect the lining of the uterus. When the lining gets too thick or too thin, bleeding often occurs. Sometimes mild and sometimes heavy. All pills are low dose, just different. So that is a very common problem.