My Gyn Requested Norethindrone Table 5mg, Which I've Been Taking

My Gyn requested Norethindrone table 5mg, which I've been taking since 8/9/18, because I have had some breakthrough bleeding although I am 57 and in Menopause. She took me off of Progesterone 100mg and before that, I was using a compounded formula so as to bypass the liver since 2012. I am currently still taking Estradiol .05mg.
I would like to know how long is it safe to continue to take the Norethindrone since this medication goes through the liver, thus perhaps adding a higher risk of breast cancer?
Also, is Norethindrone similar to Provera?
Thank you!
Sandra