I am a 23 year old mother of 4 small children... my periods are never regular, which makes it very hard for me to know when I may ovulate... my last period was on 10/30/2008 and nothing since then, not even spotting, just cramps that felt like my period was going to come... had unprotected sex on 12/1/2008 and was wondering if I could have been ovulating and have gotten pregnant? Feel pregnant, but 3 negative pregnancy tests... is it too soon for me to be testing by urine if I had unprotected sex on 12/3/2008?

It is probably too soon. Since you have irregular periods, you will just have to wait a little longer to take a test and get an accurate answer.