My last period was the 5th November.. I'm on a 28 day cycle and I'm never late, so I should have been due on the 3rd of December it's now the 10th. I'm a week late but I've take 4 tests all negative!! I have lower back pains and cramps but no period.. I usually get pms symptoms a week before I'm due and I know I'm due but I haven't had my normal pms symptoms help??