Can i be pregnant if i only had sex for my first time ? ?

I had sex for the first time on june 6 , 2011 and like a week later I started feelin a lil weird I was bleeding but I dnt think it was ma period cuz I usually get ma period for 6to7 days and I only was bleeding for 2 days . My boobs were tender I still get really tired I get dizzy a lot but I dnt know if I am or not pregnant . I really need a good answer please help mi .