With DS1 I had nothing. No sore boobs, no cramps, no nothing. With DD1 the only thing I had was that I was in the car a week before af was due and I was trying to read and felt really sick, and I thought, that's weird - I am never queasy. I thought, maybe I'm pregnant ?!
After I had missed my af, I did have a lot cramps in the following week, but I didn't bleed at all.
With the latest pregnancy #3, I felt a bit sick (no sore boobs), and I had cramping a few days before, but then af just didn't come. I thought uh oh (because it was an accident).
Good luck !