how soon can u tell if ure pregnant???

i threw up thursday n mah stomach as been in knots....i had sex tha 26th n 27th (unprotected)....its going to be 2 wks on tha 9th??? so can ne one tell me...mah friend told me to take a test tha 1st of feb....n i lost track of mah period ever since i turned 13 but im 18 almost 19 in feb...


thanks!!!