still no period...

my period was due August 13.. I tested a week ago and got a negative. when should I rest again? the past few days I have been burning up, cant stand on my feet for a long time.. I was going to wait until September 13 and see if it comes... I just moved to NC with my husband and we weren't trying for another child being we live with his grandparents and mom right now till we get our own place and if I'm pregnant it's going to be very rough.. I'm not sure if it's just late from being stressed or what. please give me some advice.