Hello, Thanks for sharing your health concern with us. Firstly, pregnancy cannot be detected soon after conception unless you have been taking the basal body temperatures from day one of the cycle. The earliest way is the blood test which can be done ten days after ovulation. In the current scenario, the most likely cause of the spotting is the withdrawal bleeding seen after consumption of the emergency contraceptive pill which will give enough protection as you took it within the stipulated time after the intercourse. You can also expect your next natural period to get delayed by a week or two and if this prolongs, please get further help from an expert. Take care.