Just a question for those who can relate out there... I had a D&C on 2/26/08 and I think I am already pregnant

I was just wondering when the dr or I could calculate the LMP? Would it date to the D&C date? I am driving myself crazy wanting to take a test NOW but am waiting until Friday, 3/28.
We conceived our 1st right away, 2 wks after going off the Pill (was on it for 11 yrs) and then MC at 8 weeks and had the D&C on 2/26. The dr told us we could try again right away and we really didn't "try" since of all the emotional turmoil we were going through, but we think it happened right away AGAIN! Which if everything is what I hope for, I will be so excited! (but cautious at the same time).
Any insight will help me relax and thank you!