Well I believe that you are pregnant, because you have all(or almost all) of the symptoms of pregnancy. Although, you should ask your doctor or take a pregnancy test to make sure.
While nausea can be an early sign of pregnancy, the pain symptoms are not. It might be a good idea to get a doctor to check if you've felt like this for more than a day or two.
your period may simply be late, due to stress, severe weight gain or loss, or a hormonal imbalance. another possibility is that you could possibly be pregnant, so seeing as how you said you already...