My suggestion would be to go to your local GP by the sounds of it no your not pregnant but it never hurts to take a second test prefferably a different brand to what you originally used, and it is natural for periods to be irregular you will have to wait and see
um you mean psychic, not physics LOL!!!! I would wait a few more days then take another test :)
No point asking us we aint physics thats what pregnancy tests were invented for !