There are many possible reasons for stomach pains, such as cramps indicating an oncoming period, cramps from infection, cramps from pregnancy, and so on. Symptoms really don't mean much, as the same symptoms are also for PMS, stress, illness, etc. Make sure to take the home pregnancy test tomorrow morning, using first morning urine which is the most concentrated. If the test is negative, then just wait for your period to come and always make sure to use protection from start to finish.
and if my period doesnt come? ive never been this late before. :/