I'm anemic, have heavy periods, mom had breast cancer. gyno gave me norethindrone & said it didn't have estrogen so wouldnt cause cancer. is that true?

Not correct: First, progesterones, which Norethindrone is one, is associated with increase risk in breast cancer (i would not state causing it). Risk is more so in women using during postmenopause and for prolonged periods. Actually, estrogen use by itself remains controversial as a risk factor for breast cancer. If your anemia is due to very heavy periods, a limited course of hormonal manipulation can help.

Don't worry: There's very little data that norethindrone causes breast cancer when used to slow down heavy periods. I would have some concern if you had a history of breast cancer, but since you don't, I'm not worried.