Implantation...Yes or no?

[Butterfly_Princess]

Can you tell me if this is implantation cramps?

20/06/07 - My BF and i had unprotected sex
22/06/07 - Approximate day for ovulation
28/06/07 - Feel period like cramps in the night, so bad had to take panadol to relieve it
06/07/07 - Period Due.

Ive read about implantation cramps and implantation bleeding etc, but the information varies from site to site, so its left me a bit confused. Ive managed to calculate that if i were to have gotten pregnant, the implantation cramps (if i got any) would have been around the time that i got these mysterious cramps. (could be wrong though)
The craps were really apparent, they werent faint or anything. They only lasted for about 3 hours, maybe more, and i thought i was getting my period early. But i didnt.
I didnt really worry about it because i know im normal down there and all. I ruled out that it couldnt have been my period because 1. it hasnt come and 2. i havent been irregular since i went on the pill when i was about 14, i am now off it however.
Just wondering what you ladies think, and if you could share any experiences with implantation bleeding and cramping?