Can micronor contraceptive tablets stop your periods?

It stopped mine entirely. I was prescribed Micronor because it's progesterone only, and I needed an estrogen free product because I was breastfeeding. Being that Micronor comes in packs of 28 with no sugar pills (and no break between packs), it never occurred to me that I should be having a period. Apparently some women do. I just saw my doc two days ago, and she was not concerned that I wasn't having periods. We did switch me back to a pill with estrogen, as they are more reliable and I am no longer breastfeeding.