Hi,I Have Been Having Pregnancy Symptoms Complete With Heart Burn

Hi,I have been having pregnancy symptoms complete with heart burn (which have never had before) and recently hot flushes.but d tests keep coming back negative. I feel very pregnant and am yet to have my period. Had sex a month and one week ago.I don't understand what's happening but I know I am not imagining the symptoms, they r real n am confused. pls help .oh am irregular with my periods,had the last one September. But then I have never felt this way before