how long after you have sex do you start feeling symptoms if youre pregnant? also, when can i take a pregnancy test? i am 17 and just worried out of my mind to find out. i get my period in 3 weeks and i really wish i didnt have to wait that long to take the test. i had sex the 21st(fathers day) and 3 days later i got my period. is there any way to take the pregnancy sooner then when im supposed to get my period again?(if i get it).