advise please!

Shaela
So I had my period around the beginning of November so anywhere from the 3-10th. I never tracked my cycle so I'm not completely sure but it has been regular( the beginning of each month) since I've got my bc taken out like 6 months ago. I was suppose to start in the beginning of December but still nothing. I've taken a few tests but they came up negative and that was about a week to a week and a half ago. Should I go get a blood test? I had unprotected sex quite a few times in the past couple of months (with the same person) so there's is definitely a posibility and I've been super tired and had been having light cramping for the past few weeks and I do get a little nacious sometimes.