I have been off birth control for over 2 years. And started having unprotected sex 4 onths ago.
The first day of my last menstrual period was on NOV 24,2010,
I was expecting my period on December 24 or 25. It's now December 28,2010
And home pregnancy tests are negative. Is my period just late?
My breast feel very tender,

It could be either way. Period may be a bit off or you could be pregnant and the test just didn't pick it up yet. Give it another week and test again if still no period. If it is still negative, see what happens when your period would be due in January. Occasionally a month may be skipped... you could see your doctor for a blood test or try another home pregnancy test before that time if you can't stand the wait... :)

Since you are trying to become pregnant, be sure to take a prenatal or multivitamin with at least 400 mg of folic acid and make any other lifestyle changes that you know would be healthy. These are important to do even while trying to conceive.

Nothing to worry! Sometimes periods just come late!