I am 16 days late but test says negative does this mean I'm not pregnant I have never been late before latley I have had som cramps and back pain .

It may be that your period is just off this cycle or it could be that you are pregnant and the test just hasn't picked it up yet.

You have some options:

*wait another several days and test again
*see your doctor about having a blood test done
*wait until next month and see what happens with your period... still no period, test again at that time.