i am late

me and my boyfriend mess around, but we don't have sex.. I was supposed to start my period Wednesday and it's Sunday... I have some cm, and a little back pain.. I'm stressing about being pregnant, but I don't think I am.. I can't really get a test because my parents are strict.. I have had some cramps, but just for a little while. my boobs aren't sore. Why haven't I started?