ovulation question

Ok so I got my period last month and the doctor had me testing ovulation days 11 through 21, well I never got a positive ovulation test but this month I did get my period. So my question is if you have your period then an egg was released and not fertilized right? And why wouldn't my ovulation tests pick up on it? I started testing ovulation as soon as my period stopped this time and I am on day 8