I have had unprotected sex last month, and started my period the day after.
My cycle is normal, and was on time the day after sex.
I have a regular period, I know when it comes, and is never late.
I am not on birth control, haven't been for over a year now.
I am not on any medication, or have done anything different than I have been doing recently.
I am now six days late on my period. I took 3 at home pregnancy test on the 3rd late day of my period, and they all came up negative, and another on the 4th day of my late period, as soon as I woke up, and again came up negative. I still have not gotten my period. I feel slight cramps, but not usual period cramps, my back has been hurting off and on through out this whole month. My nipples are tender, but I have not felt nausea at all, but I have been sleeping a lot more than usual.
Could I be pregnant, or am I just over thinking everything?
Please help.

I am trying to have a baby.