Hello I'm 32 yro, my boyfriend and I use the withdrawal method, the week of ovulation we only made love once, I'm very regular, but about 6 days ago I experienced some light bleeding that only lasted 2 days, stopped the 3rd day and had a little of spotting the 4th day, I was supposed to get my regular period 2 days ago but nothing yet, my question is, what are the chances of pregnancy?