.... Nerve racking!

Last month my period came 7 days "early"... I had sex on my calculated ovulation date.According to my period was supposed to come again this past Friday but didn't. No cramping etc. Took two rexall tests but says negative =/ How on earth am I supposed to keep track of ovulation if my period isn't consistent ??

I'm waiting holding out hope that we may still be pregnant, but I don't want to keep stressing.