i think i might be pregnant

um hi im 18 and i had unprotected sex with a friend i already had my period that month but 3 days after i had sex there was this brown stuff n i went 2 the doctor and she said she doesnt think its my period she thinks i might be prenant so she did a test n it came out neg but it would of ne ways coz it was only 5 days after i had sex i had the brown stuff for like a week and then i started to bleed like a little i had bleeding for over 16 days it jus stopped and i know it wasnt my period coz i get my period every 5 weeks and it was 2 early for em n i had already had em dat month n i get bad pains n stuff but i had no pain n it was really light not like a period ne ways now my belly feels weird like its gettin tight n when i lay down i can tell its gettin hard its been 5 weeks since i had sex n im so scared i cant stop eating im always sleepin im so tired i get headaches n d first few weeks i felt really sick like i was gonna throw up n i was like weak im so scared coz i kno some 1 dat was bleeding for 2 weks n then a week l8er found out she was pregnant i kno we should of used protection but i was drunk n yer u kno how it is i wasnt thinking plz help me i cant tell my mum she will kill me n b so disapointed