I'm three days late, not usual. I have headaches, lower backache, cramps on and off, moody, excessively tired, sore breast... I've taken a couple test and they all day negative. But I feel so weird.

Give it another week and see if your period is just off. Try another test at that time if still no period. If still negative, either see your doctor for a test in the office or a blood test, or wait until the following month to see if your period shows. Some women will skip a cycle now and then, often for no apparent reason.