So on July 5th, when you expected your period it didn't show, but you did get light cramps which lasted about a day? Since you were so late when you took the test, then it's most likely accurate. You can however get a beta blood test done at the doctors if you still suspect you're pregnant. If you're not, but really think you are, that itself can delay a period. Our minds are powerful things. Stress, hormonal changes, diet/weight change, infection, illness etc can all delay a period.
its possible however so many other things besides pregnancy can make a woman be late or miss her period(weight changes, stress, hormonal imbalance just to name a few) so its impossible to say for sure why you aren't getting yours you should wait a week if you still don't start take another pregnancy test