late period

Ok, so I'm a week late for my period. I did a test yesterday and it was negative. For the past week nearly I have been having the usually symptoms of coming on my period but each day nothing comes. Me and my partner have been trying for over a year and a half now and was really hoping that this was finally our time. So to see that negative again was dis heartening. Has anyone else been this late for there AF to start and had a negative reading. I bought a good pregnancy test and not a cheap one.