you could still be pregnant. Some women have their period the whole time they are pregnant. Also one of the signs of pregnancy is abnormal period. You need to wait about 3 weeks or so and take a test. It is probably too early for one now.
No you wouldn't be pregnant, if there's an absence of your period, that is when you worry, i'm 28 and still am very irregular so don't let being early scare you, it has saved you the scare that alot of young women get when they are late. I know how scary it is when you're young and something in your body is suddenly different and does something a little out of the ordinary, but if you are ever worried the best thing to do is get a home pregnancy test and that will ease your mind. The best thing you can do is to use this scare as something very positive and make sure next time you are more careful and use protection as there are bigger worries that just pregnancy. We all make mistakes, so just use it as a learning experience, and not repeat the mistake again like so many people do. Take care. :-)
If you're on your period than no. When you're young your periods wont always be normal. But at what at whatever age you are you need to get onto some type of birth control or use condoms. You are way to young to be worried about having a child if your old enough to be having sex than I'm sure your old enough to educate yourself.