Im on my 4th pack of low dose tri sprintec birth control with one active week left. im spotting. i read spotting usually goes away after third pack? can that take longer for some women? i dont want to increase to too high of estrogen at my age

Might take longer: The menses which occur from oral contraceptives are "artificial", from the hormones in the pill. Most women will "adjust" within 3 cycles and stop spotting, but not all. It is not dangerous, and you may choose to put up with it. Slightly different hormone combinations in another pill would likely resolve the spotting. As long as your don't smoke, the level of estrogen is not a concern.