My miscarriage occurred at 11 weeks, although the pregnancy had stopped developing sometime before then, I believe, since no actual baby was detected in the u/s I had after my spotting started. I did not have cramps at all, believe it or not. It was a pain free experience for the most part, except for some of the things they did in the ER.
What I had was stuff that looked like pieces of raw liver at first, then big clots that I could feel sticking in my vagina. I had to reach in and pull some of them out and they would start to break apart which gave me the willies. I actually reached into the toilet when I passed the largest clot which was several inches long and kind of fetus shaped, even though I know it wasn't a fetus. I just had to make sure, though.
So was that too much information? Sorry.
I've heard that you can get a positive on a pregnancy test but then get your period more or less at the regular time as the zygote (or fertilized egg, what ever the proper term is) doesn't implant and pregnancy doesn't actually occur. I would assume in that case that it would just be like a normal pregnancy. I've also heard where women continue to get light periods even though they are pregnant. If you are taking the minipill and got your period so much sooner than you should of, it sounds like something is out of whack with how the pill is working, at least.
I would think if you were feeling nauseated due to pregnancy, you'd be several weeks along which would mean that you should have gotten a positive test, but maybe not. I don't know, it's all rather confusing to me.