OOOHHH it's a hard one.
For all of my pregnancies (8) I have felt like my period is just about to arrive.
However that's how I feel just before my period arrives also.
So, it's a hard one!
Many women report that they feel cramping around day 5-7 when in a large number of pregnancies that the embryo implants...
If you haven't had a positive opk does that mean that you have had 'clean sticks' - nothing on the stick except the control line???
I hope your cramping meants that your uterus is irritable because of implantation. Keep us posted...
Hugs