Is my girlfriend pregnat?

okay me nd my gf had august 15 2010.. we didnt use a condom and yeaa i was preing in her like all guys do but for sure i didnt *** in her i pulled it out before i did that...Now today its august 29 and she is soppose to have her period on the last week of the mounth..she has been telling me that she has been feeling wierd stuff in her stomach and she sometimes feels like throwing up..my friends tell me that she probally fells like that becuase she is scared to be pregnate....What are the earliest siptoms of pregnacy for a gurl who is 15 years old ...plss let me know soon