Have you take a home pregnancy test? That is the only way to find out if you are pregnant or not, as no one here can guess as to whether or not you are. Symptoms really don't mean anything, as I get "pregnancy symptoms" just about every month, but I am not pregnant. These same symptoms can all be caused by hormonal fluctuations, PMS, stress, illness, and so on, and does not just indicate pregnancy. Take the home pregnancy test after a missed period or at least 2 weeks from the time you had sex to get an accurate result. You can get a home pregnancy test at any local pharmacy, so go buy one and use that. If the test is negative, I suggest you look into birth control methods.
Reading this I have the same problems I'm 15 but I took 4 home tests and they all came up negative but the best thing for you to do is to go get a blood test.