Extremely early detection of pregnancy?

I seem to have a weird thing that happens when I get pregnant and was wondering if anyone else has had the same experience. This will be my third pregnancy and with both of the previous ones (and this one too, granted I am pregnant), I know in my body very early. I am talking five to seven days past ovulation. I know medically it doesn't seem possible, but this is the third time I am crampy on day four or so and then I have a generally ill feeling on day five or so. I won't be able to test until Friday (at the earliest), but I am about 90% sure I am pregnant again (we intended to be). I also always get positives early on the pregnancy test (DPO 10). And I am not 'confused' as to what day I concieved, I always know based on my cycle and when we baby dance. Anyone have the same sense??