TTC #2 Please help!!!?

DH & I are TTC #2 after M/C. I miscarried at about 8 weeks on 2/11/11, by tracking my CM I ovulated on 2/28/11 We started BD every other day on 2/24 until 3/3, for about a week now my have been sore I have had waves of nausea, increased CM, I have been dead tired & a bit emotional, I have no signs of my period coming & I believe I should have gotten it today. I took an hpt on 3/10, 3/11 & 3/13 all negative, could it still be too early to get a positive?? Or is my cycle just off due to the M/C? Please help & thank you in advance!!