Pregnancy symptoms can i be pregnant?

hi everyone I'm 13 days past ovulation yesterday i took a clear blue digital test but i didn't use first morning urine and it said not pregnant. i have been having sick feelings, more cm than normal, feeling tired, moody and the worst is that i have had diarrhoea and twinges in abdomen. just wondering if this is a sign i could be pregnant or that period is coming. when should i test again?