My period came 1 week early ?

Okay so im not here for a lecture on having unprotected sex or anything like that please, i just really need your help on something.. My last period ended on the 26th of May. I had sex with some guy on the 28th of May. Since that night i have been so scared i could possibly be pregnant (i have been feeling sick and restless and random tummy cramps - or i could of just been worrying too much). I always get my period on the exact date expected and this time it came 1 week early exactly - the 16th of June. In any way could i be pregnant, is there anything i need to be worried about or do ?