It sounds like you guys are really safe

The amount of time it takes from cramping to actual AF differes from woman to woman, and often from month to month.
I do think you are being a bit worried, with how cautious you are, but if it will ease your mind, go to the store and buy a home pregnancy test. The worst it can do is confirm what you're fearing, and that will only set you on your way to getting help faster.