You wouldn't get pregnant that quickly for a start. Conception can take up to a week to occur and doesn't just happen the moment you have sex. There are various reasons for spotting to occur...infection of some kind could be one and if you are having unprotected sex then it would be worth getting checked out for that just in case. You don't sound very educated in sex, so it would be worth educating yourself a little more in it before engaging in any more of it and then this 'scare' wouldn't happen to you again. You should also be using condoms at all times to protect against STI's and pregnancy. Birth control is also something you might want to look into.
no its normal to have spotting .
I wouldn't worry about pregnancy right now..you had sex two days ago and you aren't late for your period so I would just relax wait until you are supposed to start and if nothe than take a pregnancy test with your first morning urine..if its negative but you still think something isn't right wait a week and test again