Thank you guys soo much :)
Anytime you have unprotected sex there is a risk of getting pregnant. I encourage you to look into different birth control options and see what's the best for you. The pill, patch, nuva ring, condoms, etc.
As for the bleeding, was it light or heavy like a full blown period? Sometimes, if it's your first time having sex or if the sex was particularly vigorous, you can irritate your cervix and cause some light bleeding or spotting that goes away in a few hours. If it was heavy like a period, it's possibly your cycle may just be off.
It would still be a good idea to test with a pregnancy test with first morning urine two weeks after the incident just to be sure and put your mind at ease.
January 3rd was only 3 days ago - the egg wouldn't have even implanted yet for you to be pregnant from having sex then. So no you can't be pregnant. Also, you got your period a few hours after - you cannot have a period and still be pregnant at the same time. You're only 15 so it's to be expected that your cycles still aren't very regular- it's normal at your age.
Stop worrying because you're not pregnant and I doubt very much you want to be at 15 so you need to either abstain from sex altogether or use condoms every time you have any sort of sexual contact.
dont worry just yet a year ago i had a scare an was two weeks late a month or two after that my period lasted like two days, i was having unprotected sex the whole time, it took 3 or 4 months after all this before I finally got pregnant. Your body might just be changing the older you get the more weird things happen. all u can really do is wait till ur next expected period an take a test.