I had sex for the first time on Dec.27, I came on my period Jan.3, but only stayed on for 1 day and bled very light (I used one pad the whole day), Is it possible that I am pregnant?

Can you provide us with more information:

1. Did you have unprotected sex on December 27th?
2. Are you using any type of hormonal contraception (the pill, for instance)?
3. When was your last menstrual period (first day of bleeding) in December?
4. Your period that began on January 3rd: were you expecting your period at this time, or was it breakthrough bleeding (bleeding in-between periods)