Pregnancy!!

I have had sex for the last 4 mouths without a Condom or the pill but every mouth I seem to still get my period even if it's abit out of wack, but the last week I had been heaps hungry and feeling sick with a back ack and a head ack, my tummy feels kinda funny and a bit wired.. I normally know when I'm about to get my period and it doesn't feel the same?? May I be pregnant!? I took a test the other day but it was negitve was I'm due for my period anytime from tomorrow?? What to do? I don't mind if I am I would be happy!! It's just I haven't got pregnant before so I'm guessing it's hard to get pregnant any help?? Please and thanks :)