Any cycle issues when starting hypothyroidism medicine?

I just started taking Naturethroid 3/4grain for hypothyroidism. About a week after I started taking the medicine, I was due to start my period. I went through my entire 4 period days, I'm taking lo-loestrin fe, without any bleeding or cramping whatsoever. It's now been almost another full cycle and I haven't seen anything. Has anyone else experienced this? I've also taken 2 pregnancy tests and they were both negative...