Its Been 8 Days And I Have Not Got My

its been 8 days and i have not got my periods yet.last month during my ovulation i was sick due to diarrhoea and had taken medicines metrogyl and oflomac. Ihave done my beta hcg dis week and its less than1.2 .And 3 hpts (morning sample) all negative. Doctor has prescribed meprate for 5 days 10mg and its the 4th day and i have not got my period . Could i be pregnant or is it due to the stress??