My period is late, HPT negative! Could I still be pregnant?

I have a 29 day cycle. It's like clockwork with me. I always start my period (medium/heavy flow) on what would be CD30. In addition, I usuall start spotting around CD27. I am currently on CD33 and no period, no spotting. I am having cramps like I'm about to start and my are sore. I have taken 3 HPT and they are all BFN! Could I still be pregnant?? I always have mid-cycle cramping and it started as usual. Everything was basically the same this cycle except I never really quit cramping once the midcycle cramping started. Also, my normally get very tender a week before I'm due; ths month they just started getting tender on CD29. Any advice would be great!!!