If it's only been 3 days you wouldn't be having symptoms yet. At this point the egg would be at the beginning stages of becoming an embryo. After a month a woman might be getting clues with breast tenderness but this also happens 2 weeks before a period.

It's very important you get on birth control pills and use a condom to prevent pregnancy and STD's. The pull out method doesn't work because sometimes a small amount seminol fluid comes out before ejaculation. Sorry to sound like a typical parent, but you don't want to have a baby this young.